For the cost of a rpi, just get actually capable hardware. Once you actually get anything running you'll wish you had real hardware.

Wayland is great these days. Love Wayland for touchsceen. Only thing missing for me is software kvm like synergy. Looks to be on the near horizon though.

I have two Proxmox servers at different sites. I use Proxmox backup server to backup full vms. Addition on-site backups as well. Just had to use my backups for the first time last week. Worked really well!