How to bind a Collection of a model to a custom control when the control is expecting a collection of an interface

[TrueMoniker]

I have a custom control with a bindable property that takes an ICollection<IMyInterface>. When I try to bind to the control with an implementation of ICollection<IMyInterface>, the initially bound value is ignored, I think because the binding fails. I'm assuming I have a binding set wrong but cannot find what needs to change.

I've setup an example project at https://github.com/TrueMoniker/Maui_IssueDemo_BindingModelToInterface_Collection. To see my error, run the project and see that the first binding works but the second binding is empty.

If anyone can suggest what to try next, I'd appreciate it. I assume I'm making a mistake so I figured I'd try here before reporting it to Issues.

For example, say I have a
MyControl.xaml

<VerticalStackLayout BindableLayout.ItemsSource="{Binding Source={x:Reference This}, Path=MyLabels}">
        <BindableLayout.ItemTemplate>
            <DataTemplate>
                <Label 
                    Text="{Binding MyString}"
                    VerticalOptions="Center" 
                    HorizontalOptions="Center" />
            </DataTemplate>
        </BindableLayout.ItemTemplate>
    </VerticalStackLayout>

MyControl.xaml.cs

public static readonly BindableProperty MyLabelsProperty =
        BindableProperty.Create(nameof(MyLabels), typeof(ICollection<IMyInterface>), typeof(MyControl), defaultValue: new ObservableCollection<IMyInterface>(), defaultBindingMode: BindingMode.TwoWay);

public ICollection<IMyInterface> MyLabels
{
    get => (ICollection<IMyInterface>)GetValue(MyLabelsProperty);
    set => SetValue(MyLabelsProperty, value);
}

When I try to bind a collection that is explicitly the interface, it works
ObservableCollection<IMyInterface> MyInterfaceInstance = new ObservableCollection<IMyInterface>(new List<MyModel>{new MyModel("the binding worked!")});

However, I binding the same setup, but with it explicitly as an implementation of the interface, the initial value is ignored.
ObservableCollection<MyModel> _myModelInstance = new ObservableCollection<MyModel>(new List<MyModel>{new MyModel("the binding worked!")});

MyModel.cs

public interface IMyInterface
{
    string MyString { get; set; }
}

public class MyModel : IMyInterface
{
    public MyModel(){

    }

    public MyModel(string mystring){
        MyString = mystring;
    }
    
    public string MyString { get; set; } = "if you see this, the binding did NOT work";
}

[TrueMoniker]

I've opened Issue 29337 for this