Episode 419 reports that Debian dropped support for the DEC Alpha at Debian 5. That is no longer true: I have Debian 11 VMs running on QEMU for Alpha, ARM664, HPPA, M68K, SPARC64, and S390x, and Debian 10 for PowerPC (little-endian), CentOS 7 for PowerPC (big-endian), CentOS 8 for PowerPC (little-endian). For Debian 11 Alpha, /proc/cpu reports
cpu : Alpha cpu model : EV67 cpu variation : 0 cpu revision : 0 cpu serial number : system type : Tsunami system variation : Clipper
and lscpu says
Architecture: alpha CPU op-mode(s): 64-bit Byte Order: Little Endian CPU(s): 1 On-line CPU(s) list: 0 Thread(s) per core: 1 Core(s) per socket: 1 Socket(s): 1 Model: EV67 Model name: Alpha BogoMIPS: 518.32 ...
I also have VMs for FreeBSD on ARM64 and RISC-V64, and many more.