Add project files.

MauiApp1/Platforms/Android/MainApplication.cs

@@ -0,0 +1,16 @@
+using Android.App;
+using Android.Runtime;
+
+namespace MauiApp1
+{
+    [Application]
+    public class MainApplication : MauiApplication
+    {
+        public MainApplication(IntPtr handle, JniHandleOwnership ownership)
+            : base(handle, ownership)
+        {
+        }
+
+        protected override MauiApp CreateMauiApp() => MauiProgram.CreateMauiApp();
+    }
+}