So I finally finished my install. Overall, I feel positive with the results.
I essentially followed HumbleMechanic for all the steps needed to disassemble to get to the coupling point for rear left/right doors to add the wires and terminals.
This should be the goto video for running new wires, whatever you need it for, through the rear door coupling points.
Also, I've attached my marked up version of one of MK7 wiring diagrams to show how I've connected it all.
Because I've done the rear footwell lighting and it came with a harness, I spliced into those wires instead of the OEM front footwell LED wires. If you have not gotten rear footwells, just splice directly into the front footwell wiring. The only OEM wiring I had to splice from was the window regulator motor negative power wire as I didn't want to bother with adding an earth terminal connection. See attached PDF.
Has all the parts and the Aliexpress listings that I purchased from.
The fit and finish is, okay... isn't as perfect as the original silver trim without ambient lighting.
Do note, you only need to shave off the seven (7) large grommets to get to release the trim to add the ambient lighting. Near the door pull handle are clips, there is no way to access the tabs these clips hold onto so be careful as you simply must pry. If you break a clip, the trim won't stick back tight to the door card.