Advice on replacing smart TV with Nvidia Shield or similar

So I’ve been using Jellyfin for a while now. I have a NAS running with a jellyfin server and I watch stuff on my PC or on my TV. This is concerning the TV… As is often the case with these low-to-mid tier smart TVs, the OS is slow and the UX terrible. The network adapter is also bad. Jellyfin and everything else about the UI...