I have that Kicker blue tooth speaker system in my 23 AT4X. Now, I never really use the drop down step gate, but I did try out the speaker system in it while I was innstalling my BAK Revolver tonneau cover. It had good sound and got quite loud enough to be usable. I was pretty impressed.
Compared to my wife's 2020 AT4 Carbon Pro truck, which she has the kicker blue tooth speaker system also, her speaker system is terrible. Not good sound and barely gets loud enough to hear unless you are standing close to it.
I don't know what GM changed to improve the Kicker speaker system between 2020 and 2023 but it is a major improvement. My wife's system is so bad, it was laughable. I expected my Kicker speakers to be just like hers - terrible. But was pleasantly surprised it was actually quite good.