Most running jellyfin would be looking for more 3.5" drive space than a mini PC can provide.

I have been happy with jellyfin server,

the jellyfin client for Android TV has sone hiccups. That may just be my cheap TCL TV, restarting the TV once or twice an evening gets it going again.

So far no issues with the server itself. Nor on an android phone.

I do not have thumbnail seeking enabled, we watch shows and movies through. But I have seen the option to enable such along with the warning that it will increase library discovery time.