This is a list of exploits or tools that can help you jail break your device so you can install Debian, or replace proprietary firmware with free firmware:
backdoor for Allwinner-based devices running the vendor's Linux 3.4 kernel
SamsungCID: Samsung eMMC exploit allowing bootloader unlock
routersploit: Router Exploitation Framework
WarOfTheWorlds: shellcode to hack Linux from a vulnerable TrustZone QSEE
Microsoft Secure Boot debug-mode: allows breaking Secure Boot on Windows RT devices
Quadrooter: four local-root vulnerabilities in Qualcomm-based Android devices
Qualcomm Emergency Download Mode based bootrom exploits: parts 1 2 3
dirtyc0w: root exploit for Linux bug that was open for 10 years (Android rooting tool)
Drammer: tool for exploiting Android phones via Rowhammer issues in RAM modules
optus-sagemcom-fast-3864-hacks: enable telnet and run arbitrary code on the Optus Sagemcom F@ST 3864 broadband modem
BitUnmap: vulnerability in Android ashmem
DCCP vuln: ancient Linux DCCP local root exploit
PegaSwitch: exploit toolkit for the Nintendo Switch
Adieu: PS4 kernel exploit
sighax: BootROM exploit for the Nintendo 3DS/2DS/New3DS
wInd3x: BootROM exploit for iPod Classic and Nano 3/4/5G
Samba remote code execution: useful for NAS/router systems running samba, use metasploit to get in
initroot: Bypassing Nexus 6 Secure Boot through Kernel Command-line Injection
Behind the Masq: dnsmasq code execution vulnerabilities
Traitor: Automatic Linux privesc via exploitation of low-hanging fruit
RootMy.TV: rooting LG TVs via a web interface
Dirty Pipe: write access to read-only files with Linux >= 5.8
WiFi vulns: Linux 5.1+ RCEs for any device that does WiFi, including scanning
bootloader-unlock-wall-of-shame includes info about how to unlock mobile phones, including via exploits
Many more can be found on firmwaresecurity.com.