While there are at least ONE (if not a few) Game engines that can output both mobile (Arm) and PC (IA) there are not all that many examples of developers doing it.
Sure, a game developed to run on Arm may also run on tablet & laptop along with a phone.
Of course there's the games that can run on at least two of the major consoles that can also run on desktops, laptops, tablets/convertables and the growing market of gaming handheld systems.
Gee - what are YOU going to develop for? LOL!!!
While Apple hardware was the first to embrace 'Thunderbolt', a Mac user can't take just any eGPU enclosure with just any GPU (needs to be AMD) and then can supercharge their graphics as long as they have a older IA powered device.
Frankly, I'm thinking Apple is having a hard enough time getting developers (non-game included here) to develop for their Tablets let alone for their M* powered laptops.
Outside of generally high DPI on their screens just about everything else about Apple hardware when it comes to Gaming is rather lame.