Just noticed that lineage is has an android TV build for the odroid c4, which is USD $54 (way cheaper than a pi) and you can get an ir remote for $5 and a case for $5.
Couple that with f-droid and the jellyfin android TV client, and that seems like it should be good, no?
Did you use the addon where you have to access Jellyfin from the Addons menu and then use the weird UI with way too many sub-menus? Their own addon where you add their repo is the best IMO, it adds all your jellyfin media (except live tv) to Kodi’s native UI/categories. So all the movies show up under Movies, get their own card, can be opened to see all the scraped online data, like actors, plot, and posters. Same for music and shows.
I personally just love Kodi. It’s UI is probably the most intuitive UI I’ve ever used. It’s just so clean and simple, and CoreELEC makes it fast and efficient. The only media format it can’t play is Dolby Vision, but all my media that has DV has other HDR fallbacks.
Then if I wanna watch something not on my TV with N2+ everything is synced with Jellyfin, so all my progress is saved and I can for example, pick up on a show where I left off watching it on my tablet with their app. A best of both worlds setup for me.