In the recent panel, the phrasing was something like “if you like guns, go to Alkenstar, and if you don’t, don’t let your players go there!” As much sense as technology spreading makes, too many fans hate them on principle.
I never really got that, to be honest. People want "musketeer" duellists with rapiers, pirates with all the stereotypical trappings, vampire hunters, etc. but guns are anathema. Okay, sure, I guess. For me these never really worked without guns in the picture.
For me, I's say decide if it's purely "dark ages", or early-mid middle ages (as firearms were there in the late middle ages already), or, if it's a kitchen-sink and truly mostly close to renaissance/early modern periods in aethetics, I'd want guns in it.
See all the above-mentioned examples, like Pillars of Eternity. It works, without breaking a fantasy setting and to be honest, felt much more "complete".
I always liked that Golarion and PF went a bit into that direction.