VeloeMonitorAvaloniaApp/VeloeMonitorApp/ViewModels/MainViewModel.cs

using ReactiveUI;

namespace VeloeMonitorApp.ViewModels;

public class MainViewModel : ViewModelBase
{
    private ViewModelBase _selectedPage = new IndexViewModel();
    public ViewModelBase SelectedPage { get => _selectedPage;set => this.RaiseAndSetIfChanged(ref _selectedPage, value); }
}