Navigation examples are missing MVVM pattern

[bartsipes]

Sample

https://github.com/xamarin/xamarin-forms-samples/tree/master/Navigation

Description

The MVVM pattern seems to be the primary pattern recommended for a real application, but all the Navigation examples do not use ViewModels. I've found a variety of dated examples elsewhere, but I can't seem to find any clear documentation on the https://docs.microsoft.com/en-us/xamarin/xamarin-forms/ help pages other than some e-books which are years out of date and have disclaimers all over about being out of date.

Steps to Reproduce

1. Open any solution under https://github.com/xamarin/xamarin-forms-samples/tree/master/Navigation
2. Do a search for "ViewModel"
3. Note that there are none

Expected Behavior

I would expect to have some more realistic examples of how to navigate within an app, not just the very basics.

Actual Behavior

The Navigation folder has some useful examples but they are constrained to just handling events, not working with ViewModels and how you navigate from an invoked ICommand.