Apparently not loads, but some are. People can get the more expensive branded stuff if they're worried or just overwrite the firmware with something like LibreELEC.

Also for that reason I prefer my current solution with a Mini-PC, though at about €150 rather than €35 it's a lot more expensive, which for me is fine as I use it for a lot more stuff than only as a media player, but since I'm a little wary of pitching something which requires quite a bit more technical expertise to use to people which might or not have that expertise, I only mentioned that option last and in passing.