[MishaalRahman]

>I wonder if CarPlay/Auto could be implemented on top of Automotive with relative ease.

It can, and already has. Google offers an official Android Auto Receiver app for Android Automotive that allows for wired/wireless Android Auto projection onto an AAOS head unit. (It requires build integration so it can't just be installed from Google Play, but it's an option for OEMs.)

As for CarPlay, there's no official integration package from Apple, but it can be done, as demonstrated by Polestar.