First try an HDMI dummy plug, in case the thing doesn’t dig no screen (classic intel firmware)
Then try Debian + Incus, less Proxmox shims to go wrong. Install Incus via the “zabby” repo mentioned on the incus install page. Search for “LXD” if Incus help/guides aren’t enough for you, they’re the same thing (for now). Providing an ISO in Proxmox is really clunky, and incus smooths that out so nicely. And again, less Proxmox shims to go wronk
It accomplishes the same thing as Proxmox (VMs and LXC containers, which are “lite VMs” for if you wanted a Linux VM), I recently learnt about it too! It is new, but it was backed by Canonical up until the LXD/Incus split so it’s very solid. Split because Canonical tried to control LXD heavily, so they forked and renamed it Incus.
I just used Incus and it’s very nice, use the profiles to create a profile for “GPU pass through” and “macvlan”, among others you’ll find you want. Then make instances as needed! It was easier for me to use than Proxmox.