I only use a pelican case for my CCR (rEvo) since I agree. I know some will take the rEvo as their carryon, I just can’t do that with my back. So it goes in a pelican case with a AirTag and a separate insurance policy lol. They are also ungainly to store/lug around.Pelican case is one of the most likely to get stolen kinds of bags. Get a cheaper non-descript carry-on for your valuable/delicate stuff. Leave the pig sticker at home.
In your carryon I would put all the scuba stuff you can in easily reachable or with the ability to be removed easily. I almost get asked to open my luggage for them to look at the regulators. So now I just preemptively remove them and splay the bag open in a tray so they can just look and go oh okay carry on.
Ditch the knives unless you are going to a SeaHunt fan convention or underwater knife fighting training course.
I didn’t see one so I’d recommend a mesh bag of some sort since hard sided cases are frequently not welcome on dive boats.