Granting permissions to apps is a good example of a feature that has been redesigned because having a display is not mandatory. In Android, permission requests are pop ups that ask the user. So how do we do this without a user interface?

Firstly, the permissions are declared in the same way as you would do for an Android app; you just add them to your Manifest.

Then, permissions are granted at install time, either with Android Studio when you are developing, or via the Android Things Console if you include the app for distribution. 

You can also use adb to grant and revoke permissions