Yaarel
🇮🇱He-Mage
I do similar, while striving for mythological accuracy, and try to have two or three different cultures interacting.I have, but I don't believe it was a great influence on my fantasy world view. I prefer to start with real history (to the best of my understanding of it at the time) and deviate from there contextually. Gunpowder weaponry existed alongside many items in D&D for quite a while historically, do it does the same in my games unless I have a good reason why not. Removing it for otherwise unexplained asthetic reasons does not work for me, particularly as I like the asthetic.
I treat gun powder as bullets that deal 1d8 piercing damage, like arrows, and in both cases a fatal shot can only happen when reaching zero hit points. Until then there is only fatigue and grazing. For explosions, I use spell mechanics.
Hypothetically, a bullet would pierce metal armor, but 5e mechanics dont distinguish between different kinds of armor anyway, so theres no need to give bullets special mechanics.