They’ve been doing that for a long time too. I worked at a Chevy dealership circa 2009 and did dealer installed backup cameras on Silverado and remote start systems on Camero. The Camero was just new key fob and reprograming. The Silverado was a new tailgate handle and wiring, if it didn’t have an infotainment system then it got a new rear view mirror.
On my Ford I was able to use a program called Forscan and activate remote entry that didn’t come from the factory even though the receiver was already included.
Even my 1998 car had wiring in place for features that it didn’t come with because it was cheaper to make one harness for all models instead of different harnesses for different options.