If it's legally considered a "pistol" then it must have a rifled barrel and also shoot .45 Colt or some other conventional handgun round, too. Not just .410 shotshells.
I see that a company makes long-barreled derringer type pistols with long (11") rifled barrels that use .410 shells or .45 Colt ammo.
They come in both single-barrel models and double barrel SxS configuration.