How to find XAML element by name or key inside XAML page in Xamarin Forms?

I have a custom control that has a VisualElement as a property. I want to set this element in XAML referring to some other control (VisualElement) in my XAML page.

Here's Custom control:

public class BlurredImage : Image
{
    public static readonly BindableProperty RootElementProperty = BindableProperty.Create(nameof(RootElement), typeof(VisualElement), typeof(BlurredImage), propertyChanged: RootElementPropertyChanged);
    public VisualElement RootElement { get => (VisualElement)GetValue(RootElementProperty); set => SetValue(RootElementProperty, value); }

    static void RootElementPropertyChanged(BindableObject bindable, object oldValue, object newValue)
    {
        // Do some process
    }
}

Here's my XAML code

<StackLayout x:Name="myStackLayout">
   ...
</StackLayout>

<controls:BlurredImage RootElement="{Binding myStackLayout, Source={x:Reference thisPage}}" />

I want BlurredImage's RootElement as myStackLayout. How can it be done?