Add project files.

AndroidApp1/MainActivity.cs

@@ -0,0 +1,14 @@
+namespace AndroidApp1
+{
+    [Activity(Label = "@string/app_name", MainLauncher = true)]
+    public class MainActivity : Activity
+    {
+        protected override void OnCreate(Bundle? savedInstanceState)
+        {
+            base.OnCreate(savedInstanceState);
+
+            // Set our view from the "main" layout resource
+            SetContentView(Resource.Layout.activity_main);
+        }
+    }
+}