Android TV boxes are the way to go IMO. Lots of replacement launchers and ways to remove all the baked-in ads and the like, even if you can't root the device.

If you're stateside, Walmart's ONN brand devices are the absolute best bang for your buck you can find. They're not locked down, so you're able to get into the proper Android system menu and disable apps and so on (including telemetry). You can even activate ADB and tinker that way, though you don't need to if you just want to install a more simple (read: ad-free) home screen and turn off all the tracking garbage.