Here in the UK, the BBC has something they call the "red button" feature - most of the time, it just brings up "teletext 2.0" with some news headlines etc. but when there's something like the olympics on, you can use it to switch between coverage of different events.

On my "dumb" TV that is not and never will be connected to the 'net, this feature works fine and has done so for years. On my friend's "smart" TV, the red button feature has been replaced by an "app" that we had to update and fiddle with to get it working, and it won't do anything at all without an internet connection despite the key feature just being a kind of switch between two sub-channels, both of which are served over the usual aerial/cable. You can't even turn this off to get the normal red button back.