Should I switch to Ubuntu server?

Thats a hard no IMO.

Even if you want to do something other than proxmox (just use Debian, fedora, or opensuse).

Its not bad from the CLI, you just need to know your commands.

virt-install --name=deb13-vm --vcpus=1 --memory=1024 --cdrom=/tmp/debian-13.0.0-amd64-netinst.iso --disk size=8 --os-variant=debian13

Will get you 1 vcpu, 1GB ram, and an 8GB drive worth of debian. If you don’t specify a path, in home under .local/share/libvirt/images it will go!

You can also then

virsh edit deb13-vm

And you’ll get the XML, where you can edit away.

Personally, I’d rather use the webgui for most things, but yeah its perfectly doable from the CLI.