It's actually probably running Android Automotive 4.2.2 (as opposed to straight android auto). I encountered this in my journey in to the Pioneer AVH-W4500nex after the internal SDcard failed (here's my post http://avic411.com/index.php?/topic/90861-fix-sdcard-failed-...)
You should have no problem using one of the available rootkits for 4.2.2. That's how I got root on my pioneer. You can find out a lot of interesting stuff binwalking the firmware. Stuff like diag menus and such, at least in the Pioneer stuff.
Yes, you can run your own launcher and apps on it. Probably stable once you figure out what customizations they made.
You should have no problem using one of the available rootkits for 4.2.2. That's how I got root on my pioneer. You can find out a lot of interesting stuff binwalking the firmware. Stuff like diag menus and such, at least in the Pioneer stuff.
Yes, you can run your own launcher and apps on it. Probably stable once you figure out what customizations they made.