Multiple NavigationPages Outside of MainPage - maui

Question

We are mostly a WPF shop currently and are exploring MAUI development for future projects. We have a need to track three separate layers of content (in addition to any necessary modal content), which each navigate and may all be visible on the screen at once.
I am attempting to work through various use-cases in a test app, and am separating cases in a TabBar. I had thought to use three NavigationPages in the VM of one tab and navigate each independently, but I am stumbling over getting even one to work, let alone three.
I have tried several different approaches, including ContentPresenter and ContentView, but here is the core of my most recent approach:
public NavTestVM()
{
NavPage = new NavigationPage(new NavRoot());
}
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="MauiAndUnitTest.Views.NavTest"
x:DataType="viewModels:NavTestVM">
<TemplatedPage ControlTemplate="{Binding NavPage.CurrentPage}" HeightRequest="400" WidthRequest="600"/>
</ContentPage>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="MauiAndUnitTest.Views.NavTestViews.NavRoot"
BackgroundColor="Coral">
</ContentPage>
The NavRoot page (the root page in NavPage) does not appear in the tab. If, in App.xaml.cs, I replace
MainPage = new AppShell();
with
MainPage = new NavigationPage(new NavRoot());
I get a page full of Coral-y goodness on startup. What am I missing to get current NavigationPage content to display, outside of App.xaml.cs.MainPage?
Assuming I can get this working, I would then expect I can just repeat the approach twice more for the other layers and call it good.