As mentioned in the Intents section,
screens in Flutter are represented by Widgets since everything is
a widget in Flutter. Use a Navigator to move between different
Routes that represent different screens or pages,
or perhaps different states or renderings of the same data.

How do I listen to Android activity lifecycle events?

In Android, you can override methods from the Activity to capture lifecycle
methods for the activity itself, or register ActivityLifecycleCallbacks on
the Application. In Flutter, you have neither concept, but you can instead
listen to lifecycle events by hooking into the WidgetsBinding observer and
listening to the didChangeAppLifecycleState() change event.

The observable lifecycle events are:

detached — The application is still hosted on a flutter engine but is detached from any host views.

inactive — The application is in an inactive state and is not receiving user
input.