WinUI 3 Create a Modal Search Form

I am looking into porting a Windows Forms application to WinUI 3. The application has a modal search form used in multiple places like the image below. This uses a modal form with code behind for flexible search logic, returning an object representing the selected item to the calling window.

I hope to reproduce something similar in WinUI 3, but have not found a way to do so.

The search form is used to assign Visitor entity to a variety of event types. The selected visitor is passed back to the calling form using delegates when the desired row is double clicked.

The search form requires code behind, and it looks like ContentDialog does not support that, so it is not an option.

I cannot find any way to create a modal form/window in WinUI 3 that would duplicate this functionality. Is it possible?

This is a common scenario in business applications, so how have people done this with WPF? I am new to Xaml, and am also wondering if there is another design pattern in common use instead of using a modal search form.

You can use ContentDialog

var yourPage=new Page();
var yourDialog = new ContentDialog() 
{ 
  XamlRoot = XamlRoot,
  Content = yourPage
};
await yourDialog.ShowAsync();

MainPage.xaml

<Button Click="ButtonBase_OnClick">Open SearchPage</Button>

MainPage.xaml.cs

 private async void ButtonBase_OnClick(object sender, RoutedEventArgs e)
    {
        var yourPage = new SearchPage();
        var yourDialog = new ContentDialog()
        {
            XamlRoot = XamlRoot,
            Content = yourPage
        };
        yourPage.contentDialog = yourDialog;
        await yourDialog.ShowAsync();

        //Get the return result of SearchPage
        var yourPageResult = yourPage.result;
    }

SearchPage.xaml

<Button Click="ButtonBase_OnClick">Return Selected Data</Button>

SearchPage.xaml.cs

 public MyResult result { get; set; }
    public ContentDialog contentDialog { get; set; }

    public class MyResult
    {
        public long Id { get; set; }
        public string Name { get; set; }
    }

    private void ButtonBase_OnClick(object sender, RoutedEventArgs e)
    {
        //Data after simulated search
        result = new MyResult() { Id = 1, Name = "a" };
        contentDialog.Hide();
    }