Unless the set top box (apple or whoever) has an aerial/satellite /Cable input you still need to use the normal TV to watch standard channels, exposing you to the UI adverts.
I had considered buying an Apple TV, but my Samsung TV does everything I want just with stupid adverts, which I won't be able to get away from if I have to swap sources to Apple TV and back to live TV
Depends where you are, but you can watch live TV on a lot of the apps for UK broadcast services. It’s less convenient obviously because you’d have to switch apps, but it’s possible (in the UK at least) to watch everything through Apple TV without having to go back to the TV’s input, although you’d still get ads from the non-BBC apps.
I use an Xbox which admittedly does have some ads on the Home Screen but isn’t as intrusive as something like the fire tv full screen autoplay ads. If Microsoft makes it any worse I would probably switch to an Apple TV. Open to other suggestions from others though.