I have checked the EBahn manual back and forth, and found 2 locations where the G28 location is mentioned.
Section 1, which was my first checkout, appears to be at the firewall. Pics:
After I kept checking, I also found it connected to the engine, as seen in the below pic:
It does see the last pic is the correct location, but the page on the manual references the V8 Bi-Turbo engine of the RS6.
I keep learning....