I don't have direct experience with either Qt on mobile platforms or Xamarin, so I can't provide exactly what you asked for. But I can provide a considered opin

I don't have direct experience with either Qt on mobile platforms or Xamarin, so I can't provide exactly what you asked for. But I can provide a considered opinion. I strongly recommend Xamarin over Qt, because even if you use Xamarin.Forms, you'll be using the actual native UI on each platform, not a mere approximation. So your app will be more true to the native look and feel of each platform. Moreover, it will be accessible to users with disabilities, especially blind users, as long as you don't implement any custom widgets of your own. (If you do need to implement custom widgets, you'll need to implement each platform's accessibility APIs as well.) True, these users are a minority, but if you can make your app work for them without considerable extra effort on your part just by building on the right foundation, then that's a win-win situation. Qt may offer the promise of "write once, run anywhere," but IMO, that should be more like, "write once, be inferior everywhere."