I see what you're getting at, but I think you probably want to look at total engineering hours per game if you want to get there. There were about 45,000 games on Steam at the end of 2020, based on what I've been able to pick up from news reports and Statista; there are over 950,000 games for iOS. Even presuming the average good iOS game takes fewer engineering hours and presuming there's more quick-buck cookie-cutter crap on iOS, there's almost certainly more engineering hours spent there than there is on any other platform.

But, I think you're still on to something. The biggest strike against Apple in this space is the same strike they've always had: they've never seemed to take gaming truly seriously at a corporate level, by which I mostly mean courting (and spending money on) AAA-class developers. Maybe this will change, but they have a very long track record of snatching defeat from the jaws of victory in this area.