I have now successfully tested Android Auto in iodéOS 6.2 (A15 base), but did have to unlock the bootloader, install magisk app and use it to create a modified init_boot.img then use fastboot to flash that, then install the aa4mg magisk module. When doing that I did apply all the stubs. So that meant I did NOT need to install any Google apps.
Android Auto did crash the very first connection, but then after that it seems stable, I could use OsmAnd and Organic Maps (I didn’t get Magic Earth to show up, I had that on another device not sure why it didn’t show), and Spotify would play songs (and pick up playing after unplug / replug).
This was first with a USB cable, but then I deleted the pairing from the car, deleted the created bluetooth pairing, and then re-paired bluetooth to the car (but kept the USB unplugged). Android Auto Wireless then kicked in, and paired up and worked as well as the wired connection.
This was on a 2024 Honda Ridgeline by the way.
In summary, at least with this Honda all seems to work for AA, however microG now reports a problem in the SafetyNet check attestation, saying “Failed: integrity check failed ROM is not clean”. Maybe I need another Magisk module to hide that or something. I guess the point is that it does work if AA is your highest priority, but I personally am not too eager to recommend it to others follow this Magisk rooting route.