- People shouldn't buy Apple hardware for the games, but there's clearly an audience of Apple users (that have these devices for _other_ reasons) for a lot of games, so supporting it should be an easy win. Source 2 already had a Metal build (via Dota 2). Valve cut away a confirmed audience larger than Steam Deck owners.

- Don't get hung up on "the M1". Apple's higher end models scale quite well, the Pro is very common and the Max, while mostly a bad investment solely for games, would scale well if there were games to run on it.

That presumes that Mac users are even interested in playing games... in any large enough numbers.