The last time I looked into it, people had been asking Google for the feature for a long time, to no avail. No biggie, I just run Waze on my phone attached to the left side air vent, and use Sync 3 which is great.
Can you hit the voice button and say to Google, "play x album from my device"? That's what I was trying to do and it does not work. Google wants you in their music store and not in your own collection.
I play music from a 128GB USB stick in the console, and AA is pretty useless for this. The Google voice assistant can't identify it and there's no way to browse and search it like in Sync. Not sure if it's any better in this version.