As a side project, I recently worked on creating a mobile app for Android (and iOS to be completed). To be honest, the development effort was quite straight forward. The development stack focused on Xamarin, because I do not know a thing about creating a native app for Android nor iOS. But, I do know C# … so, for me this was a natural choice :-)
My knowledge in the area of Xamarin was quite limited and I did not create an app for Android or iOS before.