Xamarin.CommunityToolkit by Microsoft

<PackageReference Include="Xamarin.CommunityToolkit" Version="1.3.1" />

.NET API 745,904 bytes

ObservableRangeCollectionExtension

public static class ObservableRangeCollectionExtension

public static void Add<T>(this ObservableRangeCollection<T> source, IEnumerable<T> collection)

To be used in collection initializer