Had a Staff Sergeant teach us a few ways to keep an auto loader in a fight.
Hooking the rear sight on a belt edge or tip of a boot sole's dress edge. To reload we would turn the pistol butt forward and tuck it in the belt to change mags. If the slide was locked to the rear at that point then you could pull the slide back in the same manner to get the pistol recharged or you could use teh slide release. This method works with pistols with exposed hammers or with striker fired pistols. You do however need to be cautious and very muzzle aware. If you shoot where there are tables , benches or counters, you could invert the pistol and charge with the muzzle pointing down range and hook teh sight on the table or bench edge and drive the frame forward.
You do need to have a sturdy rear sight for this method and it has to have enough of a shelved face on it to get good purchase on the lip of whatever you are using for charging it. Novak and low snag sights do not work well for this method.
Another option is to have a gunsmith install a charging handle in a dovetail on your slide. Some competition pistols run a type of charging handle in place of the rear sight, when red dot optics are used. Or there is this version that attaches at the rear of a Glock slide: