Just adding something here. I've also had the Swingbox on a couple different brand trucks and they served me well.
Vevor has an almost duplicate version for under $100 listed as 2019-2021 Silverado.
All the Q&A on the site from the Vevor folks say this will not fit AT4's or 22-25 model years. They've probably lost a ton of sales because it fits exactly the same as the Undercover Swingbox. I mounted one on the passenger side of my 2023 AT4 1500 in about 10 minutes and love it. I can tell no difference in the quality vs the $200+ Undercover case.
I've never ever used that driver side grab handle and am considering removing it so I can install the drivers side.
Vevor Swing case