I'm hoping reintroducing bodyweight one-legged squats back into my workout as well on a separate day might get back to where I was before.
I doubt pistols will help you get your squat strength back up, its more of a technical exericse than anything else, I know people who can squat 3x their bodyweight yet cant do them.
Train, eat, rest, repeat. If all of these variables are correct then keep doing normal squats and the numbers will come back