using System;

using Xamarin.Forms;

public class Program

{

    public static void Main()

    {

        Xamarin.Forms.Device.BeginInvokeOnMainThread(AbrirPagina);

        // Ou 

        Xamarin.Forms.Device.BeginInvokeOnMainThread(() => 

                                                     {

                                                        App.Current.MainPage.Navigation.PushAsync(new MinhaPage());

                                                     });

    }

    public class MinhaPage : ContentPage

    {

        public MinhaPage()

        {

            // InitializeComponents();

            // Aqui seria a sua página...

        }

    }

}