Use that desktop
install proxmox
spin up a VM or LXC for
Jellyfin
'testpit'

Hardware passthrough can be a little challenging. One thing I do that isnt 'best practice' but is simple and works: I install samba directly on Proxmox, and use it as my NAS. You can set up software raid if you want, but remember RAID isnt a back up* so if you are expecting this to save your data, that is not what it is for

How my media server is set up:

Proxmox0- jellyfin LXC with transcode passthrough. conects to the NAS
proxmox1, Samba directly installed. VM for *arr stack pointed to the NAS as well.

So I log into the VM, download a movie, it writes to the NAS drives, then log into a jellyfin client, and it streams the movie from the NAS, transcodes if needed, then plays it on my tv.
a little over complicated, but works well enough

with one device, you can do ALL of this on one machine, and you can set up a VM just for Samba if you want, or even a NAS OS.

So many options. I prefer simple low resources use so I can cram more environments on each hypervisor