From the article @HoopThrower linked, it looks like they were more of a hand cannon, and some even worked as a polearm with a blade or point on the reverse end.
A unit with a primitive gun and strong melee capability is exactly the role of a musketeer.
It doesn’t seem like the unit was Korean though, it looks to be purely Ming. But it could be cool to have a Divine Machine Battalion card for China that swaps out some of China’s very primitive units with more advanced gunpowder ones. Changdao could be replaced by Three Eyed Gunners that act as a musketeer unit and Flamethrowers could be replaced by a Hongyipao cannon. Or maybe it could just add the units as a new banner army in the Castle.
I’d also like to see Chinese Arquebusiers renamed to Niǎoqiāng so that Arquebusiers could be a European unit instead.