The Secret Service either used a version of this type of gun (compactly concealed in a shoulder rig under thier suitjackets(for protectin’ the prez)), or at least toyed with the idea of it’s use.

I believe the handle (with clip) was stationary and the barrel and stock folded out to lock into place. It didn’t have the spiffy light and handle though. Don’t believe it was springloaded either, but the design is very close to the FMG9.

I first read about this type of gun in a gun mag, but I can’t remember the title or issue. Think it was in the mid to late 80’s or maybe early 90’s.
Think I still have the issue, but then I have ALOT of issues of MANY gun magazines.
If I happen across it, I’ll post it, but don’t hold your breath.