Xamarin Native Architecture

Question

I need some guidance with respect to Xamarin Native Project

The Plan is:

1. UI Development:

• Xamarin.iOS with its independent UI - ie: UITableView / UICollectionViews, etc
• Xamarin.Android with its independent UI - ie: Listview and Adapters / RecyclerView, etc

2. Architecture:

• MvvM without any framework just the plain MvvM patterm
• Similar to Xamarin.Forms where we set first page in App.xaml.cs

public partial class App : Application
    {

        public App()
        {
            InitializeComponent();
            MainPage = new MainPage();
        }
}

Which means,

How do I set my first ViewModel as start page for both iOS and android in App.cs

For my Xamarin Native App.

Without using any MvvM framework eg: MvvMCross / MvvMPrism / MvvMLite

Thanks All.