I had the same experience with my parents. They have a Samsung TV and the Jellyfin experience was awful.
I ended up getting them a little N100 mini pc and installed Bazzite and the Jellyfin app from Flathub. You can configure it so it knows it’s on a TV, and responds to keyboard controls. I got them a remote from a company called Pepper Jobs that gives keyboard input and now they have a great experience with it. Even my mom, who’s a big technophobe, loves it.
My dad also has an LG TV in his workshop that doesn’t have a working Jellyfin app (cause it’s ten years old), and he uses the Jellyfin app for his Xbox on that one.