Oh I haven’t made the leap yet due to the jailbreak apps but I’ve seen read that Jellyfin is decent on AppleTV, about as good as anywhere else. Probably not as polished as you’d expect on AppleTV but serviceable. I’ll update if I end up buying one!

I second the AppleTV recommendation based on your disgust with the Roku UI ads, I am completely on your side there, but my similar search has bought me to AppleTV.

I currently run Amazon Fire Sticks which also have UI ads but my pihole is catching most of them and it’s dirt cheap with h.265 support. Plus it runs various hacked apps like TVMob, Cinema, and Cyberflix. That’s what keeps me from moving to an AppleTV or an n100 box already.