This one was just a matter of time.
I've not yet performed a hands-on test on the clumsily named CTMD43 from Intraphex, but it places a 4.3-inch smartphone-like touch-screen on the left half of the mirror; it fades away when you don't need it for full-mirror use. You can see it in action here; as of this writing it was not posted to the Intraphex site yet.
When it's on, you see a touch- and voice-controlled nav system that is largely the same as in some current Subaru cars: functional, if not state of the art. It will also show the optional rearview camera when you're in reverse.
If you have a hot spot in the car, the mirror will connect to it, allowing Google search for places to navigate to.
At $900, the list price is steep, so shop for a deep discount. Shops will be the main point of purchase for this mirror, but you know how things get out for sale on the Internet, and I bet it isn't too hard to install.