I'm actually fine with firearms, printing presses, trains, and airships, as part of a medieval set up, sort of a medieval+, though I won't necessarily have them all in there (especially trains, but airships I'm more okay with for some reason).
I use a basic medieval set up because I like having questing knights, and wizards, and rogues, there's just something I like about having these sorts of heroes in a backdrop of, somewhat feudal, castles and domains. My settings aren't exactly like it, I've introduced basic firearms before and like to include additional things like broadsheets,which could be magically created but throw in a printing press and that's also good for me, and coffee houses.