Kelgren's premise with the Grendel P10 is often missed. He was marketing the pistol to those who would only swear by a .38 snub revolver for their intended purpose, and one such group was LEOs seeking a good ankle BUG option. At the time, many (including this one) were hesitant to strap an autoloader down there due to concerns over external controls (magazine releases and safety levers) being accidentally actuated during the rigors of police patrol. Kelgren thought that these officers, as well as civilians licensed to carry (Florida, the company's home state, had just passed its landmark concealed-carry law) would like something with the simplicity in firing that the J-frame had, pull, point, and "press-to-play." But Kelgren's offering would deliver this in a package that was lighter, flatter, easier to conceal, and offered more than twice the round count. There was no magazine release and no safety lever; the only external control was the slide stop.
Rapid reloading was not a priority. Truth was, it wasn't much with those J-frames as well; few cops with an ankle gun had a reload for it, and probably just as many licensed civilian carriers did also.
The gun was directly marketed to my agency at the time, and several of us got into the deal. It was indeed less than reliable, and holster options were limited. On top of that, the company's limited size and marketing abilities prevented further development.
I carried mine back then in a pocket sometimes when off-duty, but never as an on-duty BUG due to the lack of a suitable holster. I still have it, along with the clips, clip alignment/takedown tool, case, grip extender, and manual. Clip-loading was never easy.