[sleepyeldrazi]

If he can comfortably move his head, might I suggest something VR related? Most of the first VR games that came out for mobile (i.e. using your phone as a VR screen) couldn't utilise a controller so they used head movement for controlling things. Usually you had e small crosshair in the middle with which you can select things by simply holding a position. I sadly can't remember the names of the games I tried but you might find them (or newer ones for newer headsets) through google. I know it's not a complete substitute but if they miss mountain walks, there are VR experiences (often videos) which simulate that. Might be interesting to try. I'm not aware of it but there might even be multiplayer ones, so that his wife can join him.