Even if that were true, if you had to choose one platform to serve in NA you’re better off selling to iOS users because they make up a majority of North American mobile phone users.
It depends on the functionality of the app. I'd choose Flutter so that I could port to multiple platforms with one code base. But, if it was a camera app like Kino then, of course, I would pick 1 platform.
Yeah, that makes sense. FWIW I think flutter is pretty cool. I think this sort of thing is only a concern when you have apps that have to use a lot of hardware specific features. Even if they wanted to bring Kino to Android it’d probably require whatever equally expensive and fancy Samsung device hardware I suspect.