if you have an old pc/laptop tying around and some storage, it`ll not cost you a penny to get up and running.Plex easier to use but more restricted if you dont pay for it whereas Jellyfins entirely free but requires a bit more work
I love pixelfed,I don't love the developer......this isn't going to do his already huge ego Amy favours
I didn't see the file sync part.for that I use next cloud.which works great but my he overkill if that's all your going to use it for
your better off spending a couple of quid on getting Symfonium and use that instead of Plexamp - Plexamps great, but Symfoniums better
The idea is still there,its just called nicotine and works exactly the same