I thought the same thing about plug n play when I installed the rear cargo lights in my 2020 Silverado 1500 WT but I was wrong. I installed the lights and plugged the wire into the lights and they did not work. I was told by the dealer that I would have to pay them $135 to program my BCM before they would work.
On the 110 volt plug there is more missing than the plug, you will also need the inverter.
If you're unable to get your hands in there to pull the red tab to you try using a small screwdriver. Then squeeze the black tab at the wire end of the plug. Needle nose pliers may help here. You appear to be showing the rear of the bed lights, so if you are still unable to unplug the light try removing the light first.
I thing to be cautious of is what connection type the GM plug has. It may be proprietary and require that you also buy the wire harness also to hook up to it easily. Let us know.