I finally took the time to figure out the annoying rattle under the driver side dash in my 2019 high country. It was the shift interlock solenoid rattling back and forth due to a crappy mounting design by GM. Fixed with a zip tie. Pic of zip tie fix below. Also put an Amazon weblink to a picture of the part below.
Buy ACDelco 15775841 GM Original Equipment Shift Interlock Solenoid: Automotive - Amazon.com ✓ FREE DELIVERY possible on eligible purchases