For a while it was Intel and ppc but similar graphics back end. Then it was Intel on both. But Mac had a special graphics back end. Now with Mac it's arm and proprietary graphics back end both. While they've been willing to put up with one or the other in the past. It's just not worth it to deal with both for such a small user base.

MS have been pretty good at putting their games in rival stores to appease regulators, I could see them trying to get them on Mac too, especially with apple playing for the games market now too with their new chips.

I've been in the games industry for 10 years, and worked for Fortune 500 companies before that. I can tell you that people assume there are a lot of "deals" between companies when realistically the companies aren't making deals with each other. Companies are still companies and attempt to make money off of the sources that they can.