I am not an expert in these little gems, but I have one made in Japan that I got as a kid probably around 1965. They were sold, at that time, in the mail order catalog of "Spencer's," which back then was a mail order only place.
I believe yours is probably an older version, and there little single barrel "deringers" are sometimes called "berloque" guns somewhat generically. This name may be related to a name for a watch fob (not entirely sure).
There is another 2mm pinfire version, which is a revolver called "xythos" that was sold both as a plain revolver, as well as in a little flare pistol survival kit. The ammo for the revolver has somewhat longer pins, as I recall, but is other wise the same as for the "berloque." I believe that the berloque may also have come as a mini flare gun.
These guns were available into at least the 1980s as I recall. I remember seeing them at OGCA meetings from time to time. The ammo for the Xythos revolver came in a little red plastic box. For the berloque, it used to come in a gelatin capsule as used for medicines. Wish I have bought more of the little guns and ammo when it was available.
The 2mm blanks are surprisingly loud. They would shoot the litle flares 30 or more feet into the air.
I think both types may have been available as cufflinks as well.
When I have searched lately, the websites that exists for collectors of the little guns suggest that the ammo is no longer manufactured, and the guns at also out of production. I can't attest to this for sure.
There is a paperback book available devoted to the 2mm pinfire guns. I think it is called "Littlest Guns," or something like that.
I wish I had more to offer, but perhaps checking on eBay under "berloque" or "xythos" is the best place to find out more.