[Android] Implemented UseMaterial3 build property and provided basic M3 styles

src/Controls/src/Build.Tasks/nuget/buildTransitive/netstandard2.0/Microsoft.Maui.Controls.targets

@@ -351,6 +351,10 @@
                                       Condition="'$(_EnableMauiAspire)' != ''"
                                       Value="$(_EnableMauiAspire)"
                                       Trim="true" />
+      <RuntimeHostConfigurationOption Include="Microsoft.Maui.RuntimeFeature.IsMaterial3Enabled"
+                                      Condition="'$(UseMaterial3)' != ''"
+                                      Value="$(UseMaterial3)"
+                                      Trim="true" />
     </ItemGroup>
   </Target>
 

src/Core/src/Platform/Android/MauiAppCompatActivity.cs

@@ -23,7 +23,9 @@ protected override void OnCreate(Bundle? savedInstanceState)
 				savedInstanceState,
 				AllowFragmentRestore,
 				Resource.Attribute.maui_splash,
-				Resource.Style.Maui_MainTheme_NoActionBar);
+				RuntimeFeature.IsMaterial3Enabled
+				? Resource.Style.Maui_Material3_Theme_NoActionBar
+				: Resource.Style.Maui_MainTheme_NoActionBar);
 
 			base.OnCreate(savedInstanceState);
 			WindowCompat.SetDecorFitsSystemWindows(Window, false);

src/Core/src/Platform/Android/MauiMaterialContextThemeWrapper.cs

@@ -5,7 +5,11 @@ namespace Microsoft.Maui.Platform;
 
 internal class MauiMaterialContextThemeWrapper : ContextThemeWrapper
 {
-    public MauiMaterialContextThemeWrapper(Context context) : this(context, Resource.Style.Maui_MainTheme_Base)
+    // IsMaterial3Enabled Flag needed for Control Level theming. App Level theming is handled in MauiAppCompatActivity
+    public MauiMaterialContextThemeWrapper(Context context)
+        : this(context, RuntimeFeature.IsMaterial3Enabled
+            ? Resource.Style.Maui_Material3_Theme_Base
+            : Resource.Style.Maui_MainTheme_Base)
     {
     }
 

src/Core/src/Platform/Android/Resources/values/styles-material3.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<resources>
+    <!-- Material 3 Base Theme (Automatically switches between light/dark) -->
+    <style name="Maui.Material3.Theme.Base" parent="Theme.Material3.DayNight">
+        <!-- For .NET 9 we opt out of edge to edge enforcement by default -->
+        <item name="maui_edgetoedge_optout">true</item>
+        <item name="maui_splash">false</item>
+    </style>
+
+
+    <!-- Material 3 No Action Bar Theme -->
+    <style name="Maui.Material3.Theme.NoActionBar" parent="Maui.Material3.Theme.Base">
+        <item name="windowActionBar">false</item>
+        <item name="windowNoTitle">true</item>
+        <item name="windowActionModeOverlay">true</item>
+        <item name="android:actionModeBackground">?attr/colorSurface</item>
+        <item name="android:actionModeStyle">@style/Material3ActionMode</item>
+    </style>
+
+    <!-- Material 3 Action Mode -->
+    <style name="Material3ActionMode">
+      <item name="android:background">?attr/colorSurface</item>
+      <item name="android:height">?attr/actionBarSize</item>
+    </style>
+</resources>

src/Core/src/RuntimeFeature.cs

@@ -27,6 +27,7 @@ static class RuntimeFeature
 		const bool EnableDiagnosticsByDefault = false;
 		const bool IsMeterSupportedByDefault = true;
 		const bool EnableAspireByDefault = true;
+		const bool IsMaterial3EnabledByDefault = false;
 
 #pragma warning disable IL4000 // Return value does not match FeatureGuardAttribute 'System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute'. 
 #if NET9_0_OR_GREATER
@@ -147,6 +148,14 @@ internal set
 				? isEnabled
 				: EnableAspireByDefault;
 
+#if NET10_0_OR_GREATER
+		[FeatureSwitchDefinition($"{FeatureSwitchPrefix}.{nameof(IsMaterial3Enabled)}")]
+#endif
+		public static bool IsMaterial3Enabled =>
+			AppContext.TryGetSwitch($"{FeatureSwitchPrefix}.{nameof(IsMaterial3Enabled)}", out bool isEnabled)
+				? isEnabled
+				: IsMaterial3EnabledByDefault;
+
 #pragma warning restore IL4000
 	}
 }