Xamarin.Forms makes it extremely simple to add a flyout menu or tab bars when using Shell scaffolding. Adding a login page or any other flow of content that is separate from the main navigation is also really easy, though it's not immediately obvious just how easy. This video shows you how to use the route parsing order of Shell to interject a login page (and a registration modal), and manage the navigation stack so users cannot use the Android back button to bypass your application navigation.

This same technique may be used to have different sets of tabs, and mix-match with flyouts or other structures of content (onboarding for example).

Resources:

• Docs: Shell Navigation