Collection View items

Create a data model that includes a property to track whether an item is "starred" or not.

public class Item
{
    public string Name { get; set; }
    public bool IsStarred { get; set; }
}

In your XAML, define a CollectionView and bind it to a list of items. Include a Button in the DataTemplate to allow users to "star" an item.

Create a ViewModel to manage the list of items and handle the "star" command.

public class ItemsViewModel : INotifyPropertyChanged
{
    public ObservableCollection Items { get; set; } = new ObservableCollection();

    public Command StarCommand { get; }

    public ItemsViewModel()
    {
        // Initialize the list with some items
        for (int i = 1; i <= 25; i++)
        {
            Items.Add(new Item { Name = $"Item {i}", IsStarred = false });
        }

        // Initialize the star command
        StarCommand = new Command(StarItem);
    }

    private void StarItem(Item item)
    {
        item.IsStarred = !item.IsStarred; // Toggle the star status
        OnPropertyChanged(nameof(Items)); // Notify the UI of changes
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged(string propertyName) =>
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

Set the BindingContext of your page to the ViewModel.

public partial class MainPage : ContentPage
{
    public MainPage()
    {
        InitializeComponent();
        BindingContext = new ItemsViewModel();
    }
}

Create a new page to display the starred items. Use another CollectionView and bind it to a filtered list of starred items.

Add a method to get starred items in your ViewModel.

public List GetStarredItems() => Items.Where(item => item.IsStarred).ToList();

Create a new page to display starred items.

Add a button in your main page to navigate to the starred items page.

private async void OnViewStarredItemsClicked(object sender, EventArgs e)
{
    var viewModel = BindingContext as ItemsViewModel;
    await Navigation.PushAsync(new StarredItemsPage(viewModel));
}