I would like the basics of an app started which has cloud storage connected to photo sharing and messaging between friend groups. I am a .net developer but have never done any mobile app development so would like the basic structure with these 2 elements built in to get me going.

Ideally, it would therefore be Xamarin based for cross-platform support and allow the use of Visual Studio, but not 100% fixed on that. Whatever is the best for cross-platform development really.