Good luck! I struggled immensely with getting it to work in an unprivileged container, especially the bind mounts and their permissions for my media file shares. I ended up giving up and running Jellyfin in a privileged container after a few days of fighting with it.
It should be the same process as for Jellyfin, aside from the steps to install or change settings in Jellyfin itself.
https://www.reddit.com/r/Proxmox/comments/1c9ilp7/proxmox_gpu_passthrough_for_jellyfin_lxc_with/
If you’ve got a docker host, nginx proxy manager is super simple. Aside from a super basic docker compose file, the rest of the config can be done via the web gui.
If you’re on proxmox, there’s a helper script for creating an nginx proxy manager lxc, and the rest can be done via the web gui as well.
I stopped using nextcloud after syncing suddenly broke for me, but in the app on my phone I could pull up the list of files with sync errors. It should be somewhere in the sync setting section.