Why did Android Remove Back button?
Google acknowledged that gestures don't work for all users. It added that gestures are harder to learn and takes some time to adjust. It also admitted that gestures can interfere with the way people navigate the app. Google also revealed that Android users love the Back button and is used 50% more than the Home button.
How to handle hardware back button in Android?
The hardware back button is found on most Android devices. In native applications it can be used to close modals, navigate to the previous view, exit an app, and more. By default in Ionic, when the back button is pressed, the current view will be popped off the navigation stack, and the previous view will be displayed.