I know it isn't a PCP, but I have a Crosman 2400 I bought through their custom shop:
https://www.crosman.com/custom-shop/
It has an 18 inch barrel, puts out around 9.5 ft/lb at the muzzle (temperature dependent), and is accurate to 25 yards with a cheap Amazon red dot sight. It has enough power to cleanly kill rats, pigeons, and doves with accurate shooting. It would work for squirrels with accurate shooting & head shots. I also put a TKO moderator on it to keep it quiet. It is a carbine stock, but you can get pistol grips for it.
Hope this helps.