> once people (i.e. grandma) changed the input to the streaming device, they couldn’t figure out how to get back to the cable box

Unless you have a remote with the magical "TV" button and you only have to teach (i.e. grandma) to press that one when the TV channels don't appear.

Not sure if this would work with cable boxes though, as they might get separated from the default TV input (as in, scanned channels) but THIS is something they should make smarter (learning the default input and assigning it to the TV button)