ParentPage.cs

public class ParentPage {
    
    public int Id { get; set; }
    
    public string Name { get; set; }
    
    public string Url { get; set; }
    
    public IEnumerable<TestPage> Pages { get; set; }
    
    public ParentPage(IPublishedContent content) {
        Id = content.Id;
        Name = content.Name;
        Url = content.Url;
        Pages = content.TypedCsvContent("somePages", TestPage.GetFromContent);
    }
    
    public static ParentPage GetFromContent(IPublishedContent content) {
        return content == null ? null : new ParentPage(content);
    }
    
}

PublishedContentExtensionMethods

public class PublishedContentExtensionMethods {
    
    public static IEnumerable<T> TypedCsvContent<T>(this IPublishedContent content, string propertyName, Func<IPublishedContent, T> func) {
        int[] ids = content.GetPropertyValue<string>(propertyName).CsvToInt();
        List<T> result = new List<T>();
        foreach (int id in ids) {
            try {
                IPublishedContent item = UmbracoContext.Current.ContentCache.GetById(id);
                if (item != null) result.Add(func(item));
            } catch (Exception) {
            }
        }
        return result;
    }
    
}

TestPage.cs

public class TestPage {
    
    public int Id { get; set; }
    
    public string Name { get; set; }
    
    public string Url { get; set; }
    
    public string Text { get; set; }
    
    public TestPage(IPublishedContent content) {
        Id = content.Id;
        Name = content.Name;
        Url = content.Url;
        Text = content.Text;
    }
    
    public static TestPage GetFromContent(IPublishedContent content) {
        return content == null ? null : new TestPage(content);
    }
    
}

YourView.cshtml

@{
    
    // Parse the parent content node
    ParentPage parent = ParentPage.GetFromContent(Model.Content);
    
    // Iterate through the selected pages
    foreach (var page in parent.Pages) {
        
    }
    
    // The property could hold a CSV with IDs for each selected page of something (eg. from the MNTP)
    IEnumerable<TestPage> pages = Model.Content.TypedCsvContent("somePages", TestPage.GetFromContent);
    
}

Kinda....

What I'm working on at the moment would be a little bit more automated.

public class SubPage: PublishedContentWrapped {

  public:SubPage(IPublishedContent content)
   : base(content)
  {
  }

  public int Id { get; set; }

  public string Name { get; set; }

  public string Url { get; set; }

  public string Text { get; set; }   

}

public class  ParentPage: PublishedContentWrapped {

  public ParentPage(IPublishedContent content)
  : base(content)
  {
  }

   [TypeConverter(typeof(MultiNodeTreePickerConverter))] 
  public IEnumerable<SubPage> SubPages { get; set; }    
}

It works... Kinda... when I use an extension method from here. https://github.com/leekelleher/umbraco-ditto/blob/master/src/Our.Umbraco.Ditto/Extensions/PublishedContentExtensions.cs

I've created a type converter from MNTP to aid with conversion but I don't want to have to add the type converter attribute. I was hoping there would be a more consistent data structure coming in from the various types.

It looks like I'm going to have to write a lot more code than I was hoping.

I'm haven't really had the time to research the different model builders, so I still prefer to create the models somewhat manual. So I don't think I can help you with something automatic.

Even though you're searching for something automatic, I've updated the Gist to shown how I would accomplish it using a manual approach.