Which they all seem to call 'welt' pocket machines... but I'll pass over that for now. Here is a video of a Durkopp-Adler and a Reece machine. There's another one of a Dison machine. I watched a few of these videos and it seems they basically stitch on the jettings and cut it open. You have to turn it, form the jettings and stitch up the pocket manually.
I don't know how much of a gain this really is because you still have to carefully position the piece of the garment the pocket is being cut into, the machine doesn't do it. On the Dison video the jettings are not even on both sides in the corners.
https://www.youtube.com/watch?v=RbzeaYKHy78