This is awesome. Great job explaining everything. I would highly recommend adding a link to the video on YouTube where they build the atm harness since they also have the part numbers for the connectors there. One other thing to add, instead of looping the gps through the whole car, you should be able to just add a fakra cable from the atm to the shark fin on the roof under the headliner. This way you don't have to route another cable all over BUT if you already are doing the Ethernet wire from atm to head unit, your method works perfectly. Also for those who are hesitant to solder the dc-dc converter for the display, I found a really nice one on mouser that works flawlessly and is very stable:
https://www.mouser.com/ProductDetail...2Jj6d99w%3D%3D