Those NAA mini revolvers don't serve much of a purpose in my eyes. The .22 rim fire is not a self defence round to begin with. Then it looks to be too easy to shoot off the end of your finger with the size of those things.
My brother had one and just for the fun of it, we shot a 55 gal drum with it at 25 yards. Much to my surprise, I could hit it every time. But to me, the 9mm is the smallest self defence round anyone should use.