Hi,
It should be sufficient to:
- install Android Auto (from e.g. Aurora Store)
- grant it the “Nearby devices” permission
- install the companion apps: Google Maps, Google app, Google TTS. The last two ones can be replaced by stubs as explained in the link shared by @AlphaElwedritsch.
- plug the device to a car, start Android Auto on the car interface if needed, and follow the setup.
There’s no need to install AA as root, as its support in iodé is implemented in a way that gives it a subset of the required privileged permisions. It is to be noted that these permissions are granted only after checking the AA signature, so no other app can benefit from them.
There are a few troubleshooting hints in this page, but they should not be required in general.