Those were released around 2011 from what I can find, OP was thinking the 1980's era.
Not trying to get into a semantic debate, but I see lots of references to them as "pepper-box revolver" or "pepper-box revolver derringers" or just "pepperbox" (there are pepperbox long arm, so to me, "pepperbox" is too vague). A few of the auctions and listings refer to them as just "revolvers" so it's possible that's how the ads/articles in the '80s referred to them.
I came across this listing
LEINAD INC. MR X01403 REVOLVER PISTOL 45/410 on a auction site and remembered this thread as it fits a lot of the OP's description: released in the '80s, flat trigger, no trigger guard, unique finish, etc .