The custom URL integration defines several options to control navigation. One of them is the back button control.
In Android programming you can make use of the back button control e.g. to switch from Sygic navigation to your app with a single click in the following way:
String str = "com.sygic.aura://back_button|my.app.package.id"; startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(str)));
The my.app.package.id defines the program (Android package) to which you switch when pressing on the back button in the navigation run.