US OEM kind was not plug and play. It required wire taps on all connections. I believe it was recalled due to possible improper cable routing at the muffler. Not sure if resolved, but this could be contributing to your dealer's supply issues. I do not have source info, just read it somewhere.
Canada OEM part (no idea why they were different) is plug and play at the tail lights, but you still have to modify / tap into an existing harness at the rear for the power supply. But it sure was nice using an OEM cable in the vehicle's harness and not having to run a new cable / fuse it. It looked very much like it was supplied by Reese / curt / etc. It looked just like the universal one I had in my last car, just with specific tail light harnesses and the pin to tap into the harness.
I installed my own. It wasn't terribly difficult by you need to be comfortable and careful of the interior plastics as pretty much the whole trunk needs torn apart for access to the harnesses at the rear of the car.