For the record, the IOS entertainment system is listed as standard equipment on the Trail Boss package, my truck has the SD reader in the center console, and the build sheet for my 2019 Trail Boss says it has the IOS entertainment package. So there is no question that I should be able to add the factory navigation to my truck.
As a side note, I have tried and for a wide variety of reason do not like any of the current Apple CarPlay / Android Auto solutions. So while some may disagree with my objective here to add OEM nav to my truck (and might even in a futile effort feel compelled to try to change my mind right here on this thread), my mind is made up and I want the factory navigation feature on my truck.
As many others with this same configuration on this forum have done, I surfed to my favorite authorized online GM part houses, keyed in my VIN, and confirmed that the "IOS Nav Upgrade Kit" "fits your car". Being confident that I could follow the trail blazed by others on this forum, I pulled the trigger and ordered one.
Unfortunately, that is where my problem starts.
When I contacted my relatively new metro-Atlanta dealership (let's call them dealership #1) to arrange to have the vehicle flashed, I was not surprised that they were unaware that it was possible to upgrade my truck. So I provided them the link to this forum showing how it was commonly done, and the link to the authorized GM part house showing that "IOS Nav Upgrade Kit" "fits your car".
After a considerable amount of time, dealership #1 eventually came back and said that they had contacted GM and that it was not possible to upgrade the IOS entertainment system in my truck, and they further explained that GM did not want the liability of supporting these upgrades and suggested I look at the gm-navigation.com aftermarket product as an alternative. When I looked at the suggested alternative, it appeared that all they are doing was flashing the GM module, convincing me that maybe I needed a second GM opinion.
Enter dealership #2.
Dealership #2 is part of a large national dealership group. Certainly, I thought, they should know how this is done, and on the remote chance that they didn't, they should certainly have GM connections that dealership #1 might not have had. So I reached out to them, and it was no surprise when they responded back almost immediately that yes it could be done, stating "If the code came with it, we should be able to program it. The cost to do it, is $243.95, that includes the $100.00 that GM charges us for the Download. We would need the vehicle for 4 hours."
However when I asked for some detail about the "the code", they replied rescinding their earlier statement stating that "... there is NO Upgrading of a Factory Radio to add Navigation! I checked with our Parts Department and they confirmed this as well. I don’t think even going aftermarket, if you can get the Navigation to work, I believe you lose some of the functions of the Radio."
So here I am. Has some type of edict been handed down from GM? Hopefully, some GM tech out there can shed some light on this very confusing situation.