Keep Coding

I've searched through numerous online posts and can't find a suitable answer for this scenario. It's a pretty common requirement. I have a Xamarin.Forms app with a login page and listing page. When the app is started, the login page is displayed. When they login successfully, I want to display the listing page and prevent them from backing up by clicking on the toolbar back button or the hardware back button.

Change the MainPage
when you start the app you should have
Application.Current.MainPage = new LoginPage();
after login, something like
Application.Current.MainPage = new MyFirstPageAfterLogin();