Not sure if its because its officially integrated into UVO yet, but I plug my iPhone into the USB and use maps on my phone all of the time in the car. The map doesn't display on the UVO screen, but the voice with directions comes through the speakers.
This works fine for me. Before I had UVO I used maps on the phone all of the time, but never looked at the screen of the phone while I was driving, just listened to the voice tell me when/where to turn. Using it through UVO is about the same, but since the voice comes through the speakers it is obviously much louder. One nice thing about it is that the music continues to play while maps takes you through your route. Whenever the voice needs to tell you to turn, the volume of the music lowers, and you hear a clear voice, then volume of music goes back up.
Now I will say that like all of us who struggle with UVO, sometimes the voice only comes through the phone even though I have it connected to the USB. Sometimes I have unplugged the phone, then plugged it back in to get it to work. Other times that doesn't work, and nothing I try makes the voice come through the speakers. (Life with UVO)
Also, the other day I asked Siri something while driving, and I think (I think) she responded over my speakers. I will have to try it again tomorrow and let you know.
But if you are looking for some type of Siri button on the UVO, or being able to hit a button on the steering wheel, no such luck. I don't think that was ever the point of Siri Eyes, but I need to read up on that. Apple Car is all controlled on the screen and wheel, Siri Eyes is not Apple Car. Everything I've done with the iPhone is always controlled by the phone directly, but connected to the USB. I even play iTunes Match, all of my music in the cloud via wifi - using cell data, but it comes through over the speakers. Skip, FF, all of the other commands are done using the phone, not the wheel or UVO screen.