Afaik no alternatives yet,
but I can offer some de-googling friendly additions which I developed/contributed to :)
https://github.com/Rikj000/Android-Auto-XLauncher-Unlocked
^ Allows to use 3th party apps on Android Auto
https://github.com/sn-00-x/aa4mg
^ Allows to use Android Auto with MicroG (open source implementation of the GApps)










You’re very welcome! ^^