I Can’t give you info on the foreskin restoration with that tool because I haven’t used it. I can tell you that my experience with PE be it manual exercises or pumping or whatever, I have found that my foreskin has grown. I was cut loosely to begin with but now it’s much more prevalent. Just something to consider.
A friendly suggestion would be to ditch that JP90 routine and start off with something lighter. I started with the same routine and it was way too much to start. There is a link in my signature for the linear newbie routine. I don’t know what if any past PE experience you have. If it is limited or none I suggest you give that routine a try to start.
Good luck.