Are they crossbow pistols though?I had no idea gunpowder wasn't supposed to work in the Forgotten Realms. There are drow with pistols in Waterdeep: Dragon Heist.
Anyway, I played Warhammer Roleplay before D&D, so gunpowder weapons in fantasy games seem natural to me. I used the DMG's firearm rules when I ran Warhammer's Enemy Within campaign in D&D 5e, and they work fine.
Drow crossbow pistols definitely used to be a thing.