I don't really know any better way to ask this question, and I admit its pretty vague and airy, but to try and break down a bit I'm very used to reading about the history of Italy and that 'Italy' was really not a country or real nation state in the idealized sense at all when unification occurred, and arguably still isn't. Too divided in terms of things like language, economy, culture, history and political organisation there are major inherent issues with treating the peninsula as a singular entity with a common history and culture, that's what I feel like I hear a lot when I read historical discussion around this topic.

And yet, even still when I read about historical discussion around this subforum, and other places I presume are well informed about such things, 'Italy' still often gets used in a fairly generic and casual manner that would seem to imply a certain kind of unity shared across the different entities like Florence, the Papal States, Venice or the Kingdom of Sicily, people aren't having to constantly preface their answers with reminders about the limitation of the concept of Italy in first place. It also seems to be a concept that was well accepted among lots of people for centuries past, well before the rise of modern Italian nationalism, Shakespeare at least frequently mentions this generic notion of Italy, like this piece of dialogue from the Merchant of Venice:

You know I say nothing to him, for he understands
not me, nor I him: he hath neither Latin, French,
nor Italian, and you will come into the court and
swear that I have a poor pennyworth in the English.
He is a proper man's picture, but, alas, who can
converse with a dumb-show? How oddly he is suited!
I think he bought his doublet in Italy, his round
hose in France, his bonnet in Germany and his
behavior every where.

The Holy Roman Empire had the Kingdom of Italy as one of its constituent parts, Barbarossa had his messy Italian campaigns, the French and Hapsburgs butted heads over the Italian wars, that kind of thing.

Would it be comparable to things like the current use of terms like 'Maghreb', 'Balkans' and 'Levant' to describe broad regions that have cultural and geographical elements that loosely bind them together? Or was Italy conceptualized as something more unified that that? I'm particularly curious about how southern Italy, Naples and Sicily, came into peoples perception of Italy since they seem to be much different from the rest of the peninsula.