Also, through the various *Kit libraries and now (sooner or later) SwiftUI, Apple is staking out a rapid-development territory that will be hard for the other ecosystem(s?) to match.

So, if you have to choose between making your app for iOS first, or Android first, then in addition to any consideration of markets which might or might not apply to your business model, you will have a very strong incentive to choose Apple for time to production.

I would love to see more serious competition on that front.