Exactly this myself. Debian lxc with jellyfin repo added, media on ZFS with passthrough mountpoints, very performant and easy to maintain.

Docker just adds layers of complexity for no benefit here

Jellyfin is also conveniently packaged as a .deb and provide a repo for Ubuntu/Debian. It’s pretty easy to spin up a Debian container, add the repo, and apt install jellyfin, IMHO easier than doing the same thing with a VM, then docker…

There are centrifugal fans that are quite flat but they intake airflow from a different axis they exhaust it from. Could still work