I tested it in the driveway and I can now release the parking brake once I put my seatbelt on. I do find it annoying that the car does anything more then put on a light regarding my seatbelt use. My Mercedes does nothing if I unclip my seatbelt with the brake hold on. It makes a single ding noise and the seatbelt light comes on.

I was entering a gated country club yesterday and needed to show my drivers license. I was in the NX so I was sure to put the car in park before unclipping the seatbelt but I did test it in my driveway and it seems to work as designed.