If you're willing to do vm's look into something like proxmox and run stuff as vm's, makes managing them and trying new things easy. For the os that's running services keep it simple and stick with Debian, if you need a gui for docker use portainer or yacht. For sharing the media files from the nas to the pc make an nfs mount entry in your fstab file so it mounts on boot. Do be advised however that if for some reason your nas is down while jellyfin is doing a scan it will be unable to find any media files and will start cleaning out metadata since without the nfs mount no media technically exists.
Honestly for your use case it would be worth keeping things simple and just running jellyfin on your nas if possible, just make sure you get one with a decent Intel cpu so you can enjoy quicksync for transcoding capabilities.
I've bought a fair amount of drives from them and have had no issues, just today I got in some seagate exos 2x18 drives from them and their packaging was as professional ever.