Jellyfin is very conveniently packaged in docker, so while it may seem daunting, I highly recommend at least trying that route.
Running an nfs mount, docker or not, should be perfectly fine. Jellyfin just uses normal storage so won’t care if it’s nfs. No real special considerations with proxmox either, especially without worrying about a dedicated GPU. Just spin up a Debian guest and go.
Try booting something different on proxmox like an ubuntu live desktop, just to make sure networking is working there. Seems like haos can’t talk to the Internet.