This particular gun - the real one in the OP - is just a Taurus .380 pocket pistol inside a polymer sleeve with the light/laser molded in it. Its nothing new (other than the shape), just another entry in the burgeoning market for this type of thing.
The game body pistol is TL-7, but at the time Traveller came out there wasn't any polymer pistol on the market, let alone one composed of entirely non-metallic parts designed to evade detection. Unless the KGB or CIA had something like that. And the game weapon is obviously made for covert work so maybe the spook agencies now have something like it.