I don’t think they would get away with selling games in the app if games were playable on Android (demonstrating Android compatibility). I think they would have to do what Amazon kindle does and tell you to go buy your game somewhere else.
Edit:
Here’s the policy. You might be right but it looks like a grey area to me.
https://support.google.com/googleplay/android-developer/answer/9858738?sjid=15164020873047119237-NC&visit_id=638803514547940454-2089146208&rd=1
Oh… I see!
I personally prefer the “also play PC games on Android” strategy so was looking at it from that angle.