I suspect the lack of availability is due to an IC required to process video from multiple cameras to create the invisible trailer view although it is possible it's due to lack of trailer camera availability or something equally minor. It would be greatly appreciated if you could look under your Tahoe for loose video connectors near the 7 pin trailer connector. I expect they would be miniature coaxial cable with FAKRA connectors.I have a 22 Tahoe Z71 that is loaded. In the infotainment system it shows the ability to add cameras to a trailer however I don't have camera inputs at the rear. I'm wondering if I could get my hands on the parts/cables if this could be plug and play since the head unit indicates they can be added. Not trying to steal your thread but if it could work for me maybe it could work for you as well.
I've given up on getting a Yukon with ZM1. I current have my salesman looking for an AT4 with max tow, air ride, eLSD, captain's seats and without rear seat entertainment. My plan is to retrofit the rear camera mirror and a custom switch module to select trailer cameras to be displayed in the mirror. It's additional work I don't really want to do but I'm confident I can make it work and IMO the mirror display is preferred over the in-dash display.