Only the 21 and 30 right now, 20 coming very soon, heck it might already be here. I don't know how much shorter they could make the 9mm frames. It's only for the 45 and 10mm glocks so far.
Glocks all look the same, handle the same, work the same. It's one of the features if you ask me. There are cosmetic differences between the various generations, different grips, etc. And of course different sizes, but a good portion of the little ones need to have barrels sticking far out the slide to be legal here.