Games are the main appstore revenue driver, and I don't think that game ports have much to do with iOs standards. It isn't like Fortnite or Genshin Impact on iPhone is significantly different than on Android.
Unity has tools that can partially help with that but their execution also sucks. You still need some half-working script downloaded from Github or some random site to deploy to Apple/Google if you don't want the hassle of using the default tools.
It's the same for consoles. It's an ungodly pain in the ass even with Unity. Godot makes some of its money by porting to consoles, for example. But I don't know if there's any money there for a scalable solution.