Annoyingly "Android Auto" and "Android Automotive" are completely different things.

Android Auto is where you can connect your phone to the car and your phone projects onto the car's display with apps and navigation.

Android Automotive is when the car itself is running Android Automotive for its infotainment OS, meaning it has access to a limited Android App Store to install apps natively into the car's infotainment system and you can sign in with your Google account.

Some cars with Android Automotive also support CarPlay and Android Auto on top of it, but GM has decided to disable those features, meaning you have to use the built-in Android Automotive system to manage your media streaming apps and pay GM for the data access plan.