If you really want a true dumb TV, you should look into the commercial TVs
Personally I just get any TV and don’t connect it to the internet. I disable any popup interfaces/home menus as much as I can on the TV so I just turn it on and it goes to HDMI1 and that is all the TV’s interface needs to do.
I also disable alot of the picture altering features as well. My LG TV has some true motion crap that just made everything a little bit off.
For the most part the handful of TVs I have tried just work.