Not GP but I have lots of fun running VMs and lots of containers on an old HP Z440 workstation from 2014 or so. This thing has 64 GB of ECC RAM and costs next to nothing (a bit more now with RAM that went up). Thing is: it doesn't need to be on 24/7. I only power it up when I first need it during the day. 14 cores Xeon for lots of fun.
Only thing I haven't moved to it yet is Plex, which still runs on a very old HP Elitedesk NUC. Dunno if Plex (and/or Jellyfin) would work fine on an old Xeon: but I'll be trying soon.
Before that I had my VMs and containers on a core i7-6700K from 2015 IIRC. But at some point I just wanted ECC RAM so I bought a used Xeon workstation.
As someone commented: most services simply do not need that beefy of a machine. Especially not when you're strangled by a 1 Gbit/s Internet connection to the outside world anyway.
For compilation and overall raw power, my daily workstation is a more powerful machine. But for a homelab: old hardware is totally fine (especially if it's not on 24/7 and I really don't need access to my stuff when I sleep).
