test/help/ViewModels/MainWindowViewModel.cs

using Avalonia.Controls;
using help.Models;
using help.Views;
using ReactiveUI;

namespace help.ViewModels
{
    public class MainWindowViewModel : ViewModelBase
    {
        static SuharevaContext myConnection = new SuharevaContext();

        static SuharevaContext myConnection1 = new SuharevaContext();

#pragma warning disable CA1822 // Mark members as static
        UserControl us = new Page1(); // по умолчанию в ContentControl загружается созданная Page1
        public UserControl US { get => us; set => this.RaiseAndSetIfChanged(ref us, value); }

        Page1ViewModel page1VM = new Page1ViewModel(myConnection); // объект для работы со свойствами из Page1, а ниже для свойство для привязки:
        public Page1ViewModel Page1VM { get => page1VM; set => page1VM = value; }
        
        Page2ViewModel page2VM = new Page2ViewModel(myConnection1);
        public Page2ViewModel Page2VM { get => page2VM; set => page2VM = value; }


        public void toPage2()
        {
            US = new Page2();
        }

        public void SaveNetwork()
        {
            myConnection.SaveChanges();
            US = new Page2();
        }

        public void SaveUser()
        {
            myConnection1.SaveChanges();
            US = new Page1();
        }

#pragma warning restore CA1822 // Mark members as static
    }
}