This page covers hardware from the UK manufacturer Softiron.
They offer two arm64-based headless machines, using the AMD 'Seattle' (Opteron A1100) processor.
This is a server in 1U case. A1100 A57 CPU (8 cores), 16GB DDR3 (RDIMM, 4 slots), 10G Ethernet, PCI express, 8 SATA 3, 1TB HDD. Supplied with ?OpenSuse Linux installed. $2500
Due to standard UEFI firmware, installing Debian is simple. ?InstallingDebianOn/SoftIron/overdrive-3000
This is a Mini-ITX desktop machine. A1100 A57 CPU (4 cores), with Ethernet, SATA 3, USB 3, 1TB HDD, 8G DDR4 RDIMMs. It makes a nice build machine. Supplied with ?OpenSuse installed. $600
Due to standard UEFI firmware, installing Debian is simple. InstallingDebianOn/SoftIron/overdrive-1000