Menu View Not Loading [duplicate]

Question

i'm struggling to get a very simple mvvm app off the ground and not sure why, imagine an app such as the below:

public partial class App : Application
{
 protected override void OnStartup(StartupEventArgs e)
 {
    base.OnStartup(e);
    MainWindow app = new MainWindow();
    MainViewModel context = new MainViewModel();
    app.DataContext = context;
    app.Show();
   }
  } 
 

And a mainViewModel that looks like this:

    class MainViewModel
    {

    public object CurrentViewModel;

    public MainViewModel()
    {
        CurrentViewModel = new MenuViewModel();           
    }
}

and the MainWindow like so:

<Window x:Class="myApp.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:myApp"      
    mc:Ignorable="d"
    Title="MainWindow" Height="460" Width="800">

<Window.Resources>
    <DataTemplate DataType="{x:Type local:MenuViewModel}">
        <local:Menu />
    </DataTemplate>        
</Window.Resources>

<ContentControl 
    
    Content="{Binding CurrentViewModel}"
    HorizontalAlignment="Left" 
    VerticalAlignment="Top" Height="440" Width="790" Margin="0,0,0,-21"/>

</Window>

with the menu Page View like this:

 <UserControl x:Class="myApp.Menu"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:myApp"
             mc:Ignorable="d" 
             d:DesignHeight="450" d:DesignWidth="800">
    <Grid>
        <Button Content="MyButton" HorizontalAlignment="Left" Margin="34,90,0,0" 
   VerticalAlignment="Top" Width="75"/>  

    </Grid>
</UserControl>

So basically, when the application loads i would like to show the menu View, but the code

 CurrentViewModel = new MenuViewModel();

inside MainViewMode is never hit, i am assuming that is why the content control is never populated with the Menu View and why the button inside the Menu is never displayed,

i can't understand why this point is never reached, what fundamentally hilarious thing am i missing?