I remember an article on a French police contract for S&W 9mm revolvers, I think they had been using various .32 and 9mm autoloaders before that.
They already had stock piles of 9mm ammo and could get 9mm more easily than contracting for .38 or .357 ammo.
The Israeli 9mm chambered copy of the Model 10 is an odd duck. Not sure if I'd trust it with most 9mm loads. The Israeli standard SMG loads for use in the STEN and other SMGs at the time was one of those that used slower burning powder to obtain higher velocity in longer barrels, which meant much powder was still unburned when the bullet left the muzzle of a handgun. The Finns used the same sort of ammo in their blowback operated 9mm Browning Long chambered 1907 pistols which caused a large muzzle blast but did not damage the slides the way standard 9X19 pistol cartridges would have.
The S&W M&P style frame would likely handle a number of standard pressure 9mm pistol cartridges before any real damage began to show, much as their .32-20 revolvers could handle a few of the .32-20 Winchester loads marked with the for rifles only warning on the box.
The similarity between the 9mm Federal rimmed case and the .38 S&W case brings up possibilities. They say you can trim a .38 S&W case to work, and some have tried the fit of the .38 S&W cartridge in the chamber of the Charter Arms Pitbull and seems to fit. If the case mouth is not obstructed by the chamber mouth it might work, or if one deepened the chamber a tad then the lack of new manufactured 9mm Federal ammo would not make the pistol useless.
An auxillary cylinder in 9mm would be a good thing to have, for .357 revolvers at least. They make a few convertibles already.
Being able to use .38 S&W as well as 9mm and .380 ACP ( & possibly the slightly larger Makarov cartridge ) with moon clips would make ammo supply easier in some areas and the pistol slightly more versatile. The chamber would be a tad loose I suppose.