This page offers some information about running Debian Stretch in the Lenovo ?IdeaPad 520 laptop with Debian Buster (was testing by the time of writting).

BIOS

With a default laptop from the vendor, Windows is likely installed as the base system. In order to install Debian, the BIOS will need to be set to disable Secure Boot. Otherwise, the USB stick won't boot.

Other than that, most of the BIOS options are standard (boot order, UEFI, etc).

Installer

The Debian Buster testing installer works out of the box in the Lenovo ?IdeaPad 520. It will complain about missing firmware for the WIFI card and video card, which is a common issue nowadays. You can solve this by using an ISO with non-free firmware included (you can find it somewhere in the debian.org).

The default Nvidia Geforce seems to have some issues with the nouveau driver. I didn't try NVidia drivers directly.

Keyboard & Desktop

Most of the keyboard shortcuts works out of the box in the desktop environment, even multimedia ones.

In XCFE, the volume buttons required to put the 'xfce4-pulseaudio-plugin' installed anywhere in the panel to properly work.

Hardware & firmware

This is a lspci run:

00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v6/7th Gen Core Processor Host Bridge/DRAM Registers (rev 08)
00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 620 (rev 07)
00:14.0 USB controller: Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller (rev 21)
00:14.2 Signal processing controller: Intel Corporation Sunrise Point-LP Thermal subsystem (rev 21)
00:15.0 Signal processing controller: Intel Corporation Sunrise Point-LP Serial IO I2C Controller #0 (rev 21)
00:16.0 Communication controller: Intel Corporation Sunrise Point-LP CSME HECI #1 (rev 21)
00:17.0 RAID bus controller: Intel Corporation 82801 Mobile SATA Controller [RAID mode] (rev 21)
00:1c.0 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port (rev f1)
00:1c.4 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #5 (rev f1)
00:1c.5 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #6 (rev f1)
00:1f.0 ISA bridge: Intel Corporation Intel(R) 100 Series Chipset Family LPC Controller/eSPI Controller - 9D4E (rev 21)
00:1f.2 Memory controller: Intel Corporation Sunrise Point-LP PMC (rev 21)
00:1f.3 Audio device: Intel Corporation Sunrise Point-LP HD Audio (rev 21)
00:1f.4 SMBus: Intel Corporation Sunrise Point-LP SMBus (rev 21)
01:00.0 3D controller: NVIDIA Corporation GP108M [GeForce MX150] (rev a1)
02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 10)
03:00.0 Network controller: Qualcomm Atheros QCA9377 802.11ac Wireless Network Adapter (rev 31)

And this is an lspci -v run:

arturo@ranger:~$ sudo lspci -v
00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v6/7th Gen Core Processor Host Bridge/DRAM Registers (rev 08)
        Subsystem: Lenovo Xeon E3-1200 v6/7th Gen Core Processor Host Bridge/DRAM Registers
        Flags: bus master, fast devsel, latency 0
        Capabilities: [e0] Vendor Specific Information: Len=10 <?>

00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 620 (rev 07) (prog-if 00 [VGA controller])
        Subsystem: Lenovo UHD Graphics 620
        Flags: bus master, fast devsel, latency 0, IRQ 130
        Memory at 92000000 (64-bit, non-prefetchable) [size=16M]
        Memory at a0000000 (64-bit, prefetchable) [size=256M]
        I/O ports at 5000 [size=64]
        [virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
        Capabilities: [40] Vendor Specific Information: Len=0c <?>
        Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00
        Capabilities: [ac] MSI: Enable+ Count=1/1 Maskable- 64bit-
        Capabilities: [d0] Power Management version 2
        Capabilities: [100] Process Address Space ID (PASID)
        Capabilities: [200] Address Translation Service (ATS)
        Capabilities: [300] Page Request Interface (PRI)
        Kernel driver in use: i915
        Kernel modules: i915

00:14.0 USB controller: Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller (rev 21) (prog-if 30 [XHCI])
        Subsystem: Lenovo Sunrise Point-LP USB 3.0 xHCI Controller
        Flags: bus master, medium devsel, latency 0, IRQ 125
        Memory at 94390000 (64-bit, non-prefetchable) [size=64K]
        Capabilities: [70] Power Management version 2
        Capabilities: [80] MSI: Enable+ Count=1/8 Maskable- 64bit+
        Kernel driver in use: xhci_hcd
        Kernel modules: xhci_pci

00:14.2 Signal processing controller: Intel Corporation Sunrise Point-LP Thermal subsystem (rev 21)
        Subsystem: Lenovo Sunrise Point-LP Thermal subsystem
        Flags: bus master, fast devsel, latency 0, IRQ 18
        Memory at 943b0000 (64-bit, non-prefetchable) [size=4K]
        Capabilities: [50] Power Management version 3
        Capabilities: [80] MSI: Enable- Count=1/1 Maskable- 64bit-
        Kernel driver in use: intel_pch_thermal
        Kernel modules: intel_pch_thermal

00:15.0 Signal processing controller: Intel Corporation Sunrise Point-LP Serial IO I2C Controller #0 (rev 21)
        Subsystem: Lenovo Sunrise Point-LP Serial IO I2C Controller
        Flags: bus master, fast devsel, latency 0, IRQ 16
        Memory at 943b1000 (64-bit, non-prefetchable) [size=4K]
        Capabilities: [80] Power Management version 3
        Capabilities: [90] Vendor Specific Information: Len=14 <?>
        Kernel driver in use: intel-lpss
        Kernel modules: intel_lpss_pci

00:16.0 Communication controller: Intel Corporation Sunrise Point-LP CSME HECI #1 (rev 21)
        Subsystem: Lenovo Sunrise Point-LP CSME HECI
        Flags: bus master, fast devsel, latency 0, IRQ 128
        Memory at 943b2000 (64-bit, non-prefetchable) [size=4K]
        Capabilities: [50] Power Management version 3
        Capabilities: [8c] MSI: Enable+ Count=1/1 Maskable- 64bit+
        Kernel driver in use: mei_me
        Kernel modules: mei_me

00:17.0 RAID bus controller: Intel Corporation 82801 Mobile SATA Controller [RAID mode] (rev 21)
        Subsystem: Lenovo 82801 Mobile SATA Controller [RAID mode]
        Flags: bus master, 66MHz, medium devsel, latency 0, IRQ 126
        Memory at 943a0000 (32-bit, non-prefetchable) [size=32K]
        Memory at 943b4000 (32-bit, non-prefetchable) [size=256]
        I/O ports at 5080 [size=8]
        I/O ports at 5088 [size=4]
        I/O ports at 5060 [size=32]
        Memory at 94300000 (32-bit, non-prefetchable) [size=512K]
        Capabilities: [80] MSI: Enable+ Count=1/1 Maskable- 64bit-
        Capabilities: [70] Power Management version 3
        Capabilities: [a8] SATA HBA v1.0
        Kernel driver in use: ahci
        Kernel modules: ahci

00:1c.0 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port (rev f1) (prog-if 00 [Normal decode])
        Flags: bus master, fast devsel, latency 0, IRQ 122
        Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
        I/O behind bridge: 00004000-00004fff
        Memory behind bridge: 93000000-93ffffff
        Prefetchable memory behind bridge: 0000000080000000-0000000091ffffff
        Capabilities: [40] Express Root Port (Slot+), MSI 00
        Capabilities: [80] MSI: Enable+ Count=1/1 Maskable- 64bit-
        Capabilities: [90] Subsystem: Lenovo Sunrise Point-LP PCI Express Root Port
        Capabilities: [a0] Power Management version 3
        Capabilities: [100] #00
        Capabilities: [140] Access Control Services
        Capabilities: [220] #19
        Kernel driver in use: pcieport

00:1c.4 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #5 (rev f1) (prog-if 00 [Normal decode])
        Flags: bus master, fast devsel, latency 0, IRQ 123
        Bus: primary=00, secondary=02, subordinate=02, sec-latency=0
        I/O behind bridge: 00003000-00003fff
        Memory behind bridge: 94200000-942fffff
        Capabilities: [40] Express Root Port (Slot+), MSI 00
        Capabilities: [80] MSI: Enable+ Count=1/1 Maskable- 64bit-
        Capabilities: [90] Subsystem: Lenovo Sunrise Point-LP PCI Express Root Port
        Capabilities: [a0] Power Management version 3
        Capabilities: [100] #00
        Capabilities: [140] Access Control Services
        Capabilities: [220] #19
        Kernel driver in use: pcieport

00:1c.5 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #6 (rev f1) (prog-if 00 [Normal decode])
        Flags: bus master, fast devsel, latency 0, IRQ 124
        Bus: primary=00, secondary=03, subordinate=03, sec-latency=0
        Memory behind bridge: 94000000-941fffff
        Capabilities: [40] Express Root Port (Slot+), MSI 00
        Capabilities: [80] MSI: Enable+ Count=1/1 Maskable- 64bit-
        Capabilities: [90] Subsystem: Lenovo Sunrise Point-LP PCI Express Root Port
        Capabilities: [a0] Power Management version 3
        Capabilities: [100] #00
        Capabilities: [140] Access Control Services
        Capabilities: [220] #19
        Kernel driver in use: pcieport

00:1f.0 ISA bridge: Intel Corporation Intel(R) 100 Series Chipset Family LPC Controller/eSPI Controller - 9D4E (rev 21)
        Subsystem: Lenovo Intel(R) 100 Series Chipset Family LPC Controller/eSPI Controller - 9D4E
        Flags: bus master, medium devsel, latency 0

00:1f.2 Memory controller: Intel Corporation Sunrise Point-LP PMC (rev 21)
        Subsystem: Lenovo Sunrise Point-LP PMC
        Flags: bus master, fast devsel, latency 0
        Memory at 943ac000 (32-bit, non-prefetchable) [size=16K]

00:1f.3 Audio device: Intel Corporation Sunrise Point-LP HD Audio (rev 21)
        Subsystem: Lenovo Sunrise Point-LP HD Audio
        Flags: bus master, fast devsel, latency 32, IRQ 132
        Memory at 943a8000 (64-bit, non-prefetchable) [size=16K]
        Memory at 94380000 (64-bit, non-prefetchable) [size=64K]
        Capabilities: [50] Power Management version 3
        Capabilities: [60] MSI: Enable+ Count=1/1 Maskable- 64bit+
        Kernel driver in use: snd_hda_intel
        Kernel modules: snd_hda_intel, snd_soc_skl

00:1f.4 SMBus: Intel Corporation Sunrise Point-LP SMBus (rev 21)
        Subsystem: Lenovo Sunrise Point-LP SMBus
        Flags: medium devsel, IRQ 16
        Memory at 943b3000 (64-bit, non-prefetchable) [size=256]
        I/O ports at 5040 [size=32]
        Kernel driver in use: i801_smbus
        Kernel modules: i2c_i801

01:00.0 3D controller: NVIDIA Corporation GP108M [GeForce MX150] (rev a1)
        Subsystem: Lenovo GP108M [GeForce MX150]
        Flags: bus master, fast devsel, latency 0, IRQ 131
        Memory at 93000000 (32-bit, non-prefetchable) [size=16M]
        Memory at 80000000 (64-bit, prefetchable) [size=256M]
        Memory at 90000000 (64-bit, prefetchable) [size=32M]
        I/O ports at 4000 [size=128]
        Expansion ROM at <ignored> [disabled]
        Capabilities: [60] Power Management version 3
        Capabilities: [68] MSI: Enable+ Count=1/1 Maskable- 64bit+
        Capabilities: [78] Express Endpoint, MSI 00
        Capabilities: [100] Virtual Channel
        Capabilities: [250] Latency Tolerance Reporting
        Capabilities: [258] L1 PM Substates
        Capabilities: [128] Power Budgeting <?>
        Capabilities: [420] Advanced Error Reporting
        Capabilities: [600] Vendor Specific Information: ID=0001 Rev=1 Len=024 <?>
        Capabilities: [900] #19
        Kernel driver in use: nouveau
        Kernel modules: nouveau

02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 10)
        Subsystem: Lenovo RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
        Flags: bus master, fast devsel, latency 0, IRQ 16
        I/O ports at 3000 [size=256]
        Memory at 94204000 (64-bit, non-prefetchable) [size=4K]
        Memory at 94200000 (64-bit, non-prefetchable) [size=16K]
        Capabilities: [40] Power Management version 3
        Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit+
        Capabilities: [70] Express Endpoint, MSI 01
        Capabilities: [b0] MSI-X: Enable+ Count=4 Masked-
        Capabilities: [d0] Vital Product Data
        Capabilities: [100] Advanced Error Reporting
        Capabilities: [140] Virtual Channel
        Capabilities: [160] Device Serial Number 01-00-00-00-68-4c-e0-00
        Capabilities: [170] Latency Tolerance Reporting
        Capabilities: [178] L1 PM Substates
        Kernel driver in use: r8169
        Kernel modules: r8169

03:00.0 Network controller: Qualcomm Atheros QCA9377 802.11ac Wireless Network Adapter (rev 31)
        Subsystem: Lenovo QCA9377 802.11ac Wireless Network Adapter
        Flags: bus master, fast devsel, latency 0, IRQ 129
        Memory at 94000000 (64-bit, non-prefetchable) [size=2M]
        Capabilities: [40] Power Management version 3
        Capabilities: [50] MSI: Enable+ Count=1/8 Maskable+ 64bit-
        Capabilities: [70] Express Endpoint, MSI 00
        Capabilities: [100] Advanced Error Reporting
        Capabilities: [148] Virtual Channel
        Capabilities: [168] Device Serial Number 00-00-00-00-00-00-00-00
        Capabilities: [178] Latency Tolerance Reporting
        Capabilities: [180] L1 PM Substates
        Kernel driver in use: ath10k_pci
        Kernel modules: ath10k_pci

The only non-free firmware seems to be 'iwlwifi' for the WIFI network card. which you can obtain by installing the firmware-iwlwifi package.