Off lease corporate thin clients with fresh ssds. You can get something that runs off a laptop power supply, will handle more than you’re going to throw at it, and they’re insanely cheap.

I moved to one from a pi when I got serious about home assistant.

I also run a stack of networking utilities on my OPNSense router.

Jellyfin has been a bit more difficult to transition, I’m still running it on my wife’s gaming computer. I’ve pre transcoded most of our collection, but not all of it. I need to find something very cheap but also capable of handling the odd 4k transcode.