This is my opinion and not from anything official, but the chip shortage is likely affecting modules that will be on the wiring looms themselves. The bumpers are injection molded and will always have the holes that a sensor would clip into, the actual sensors themselves likely are not too affected by shortages and would be installed it's just that the harnesses likely wouldnt be installed inside the bumper. This would be a 1hr book job to remove the bumper clip in the harness and plug it in. Again this is just my speculation from looking at parts diagrams and my experience currently working in automotive engineering and working with supply constraints.
In the diagram, parts 4,5, and 6 are things that may have chip constraints. These all are modular and clip into the bumper. The actual sensors are quite dumb and will likely ship in the bumper so from the outside you wouldn't notice anything was different or missing. Again MY opinion not GM's.