ASP.NET Zero includes a basic Xamarin application source code that is fully integrated to the web backend and uses same APIs, permissions, localizations, settings and so on. You can get it as the base for your integrated mobile solution for your application.
Notice that the Xamarin solution is only available for ASP.NET Core backend (not available for ASP.NET MVC 5.x).
- Development Guide to understand the solution structure and start your development.
- Step by Step Development tutorial leads you to develop an application step by step.