Thank you to everyone here for the great information. I figured I'd share my experience here.
Recently purchased a 2016 Ram 1500 Big Horn. Had the 8.4 RA3 without navigation. I really missed Android Auto so decided to upgrade.
Step 1: Find Radio
After a few weeks of watching found a UAS (68331635AH) for a good price from a salvage yard. As a bonus they even included the small radio bezel and automatic temp controls. Screen had some oddness like it was cleaned with a chemical that made spots on the screen where it was used a lot look odd. Figured it was just the factory screen protector. Tested the radio and everything worked well after a couple of restarts. Heated Seats, automatic climate control, and backup camera all worked. Decided to peel the screen protector (razor blade, hair-dryer, and aircraft decal and adhesive remover) and now looks like new waiting for a new screen protector.
Step 2: USB Hub
Decided to order the Dual-USB, Dual USB-C hub off ebay (68397098AE). Found one relatively cheap. Plugged it in using the great adapter cable from M2 Mods. The USB wiring harness on the truck did have two small flat tabs sticking out the end of it. I had to clip them off with a wire cutter to get it to fully seat in the new hub. Plugged in the phone using a USB-C cable and Android Auto launched.
Step 3: USB Hub Adapter
This is the current step I am on. I am working on a 3d model to print an adapter for the usb hub. Printing a blank prototype now and we'll see how it fits. Then the fun starts trying to fit the hub into the adapter. If things work out I'll share the print files or the models for others to use.