In the old days of com.nokia.meego or even now with the Sailfish.Silica module you are using the "Pages" for navigation inside the app.
What should be used instead when developing a mobile app for Android with the Qt Quick Controls?
It really depends on your needs, I'd say for basic apps a simple TabView will suffice, for more complex dialog design you will probably need a StackView.
Naturally, you can also nest one into the other.
Lastly, with QML it is easy enough to implement your custom app navigation system using dynamic object instantiation, animations and effects.