I need a super simple solution for a stb

I want a very simple set top box solution that can be plugged in to HDMI1 on a TV and that has a super simple interface so that someone who isn't tech savvy at all can use it. My thinking is, if they know to turn on the TV and can then just navigate around live TV channels (don't want anything else) that'd be great. I want to be able to configure/limit the channels they have access to to keep it as simple as possible.

Can anyone recommend a hardware solution that can do this? Thanks!