ANR - Activity Not Responding happens on Android when you block the rendering/main thread for 5 seconds or more.
I'm using MonoGame which is built on top of Xamarin and I'm using the Xamarin Profiler.
I can repro an ANR caused by input by rapidly moving a controller axis during the Activity and Game initialization.
The Xamarin Time Profiler is handy which tracks the cumulative time spent in particular methods.
In my case though, I'm searching for any function or method that takes 3 or more seconds to execute.
This would be a handy feature to add to the Xamarin profiler which would help find any slow methods on the main thread.