You can get a Mini PC with a modern laptop chip inside it to get the power savings and save some space too. Not only that, but you get the advantage of a potentially more modern chip too. I tried my new setup (Ryzen 5 5560U) with 4K HDR decoding last night and it worked without a hitch.
I migrated from Plex to Jellyfin years ago and haven't looked back. It might play better with AMD hardware but I can't say for sure. All I can say is that I spun up a container and it Just Works™