that is a Google hold up and not in control of home assistant. Android Automotive has support for it when the car is parked and if the car does not have the Play Store.
you can: https://companion.home-assistant.io/docs/android-auto/#favorites
Google does not allow this either (see image usage): https://developer.android.com/docs/quality-guidelines/car-app-quality?category=iot#app_categories