This is very far from being true as a generic statement. My parents are around 80 and they are not the only ones of this age I know who can use these devices pr

This is very far from being true as a generic statement. My parents are around 80 and they are not the only ones of this age I know who can use these devices pretty efficiently. (They both have an android smart phone plus they have a Linux laptop. They use these all the time. Oh, and they watch content and listen to internet radio on their Kodi running on a RasPi.) Of course not all 80 year old will be able to use these efficiently or, for that matter will like using them, but that's a different story. You can still make those easier to use (e.g. with a customized android skin/ui) or build a thing that somewhat looks like an actual but specialized computer.