I dont think germany was seen as much more internally unified as italy.

I think they did an overall better job post unification to bind the people together under one identity. Like universal conscription sending you across the country, or a far more integrated economic system, with railroads spanning the length of the whole country instead of just connecting important points or all leading to the capital like france.

But especially at the beginning, germans didnt see themselves as just german either. Best example there is is probably elsas. Troops that were stationed there from other parts of germany had rude derogatory terms for the populace and looked at them more like an occupied people then equalls in germany. Due to this and a huge economic issue being in the german market instead of the french one all of the sudden, lead to Elsas germans not really feeling as a core part of germany.

Remember, elsas was 80%+ german speaking when they got annexed in 1871 and after that more then 50000 people left to go to france, presumably almost all french speaking to make this german majority even more decisive. Meaning that even a region with a vast majority of german speaking people, was still not well integrated and seen as "truely german". Elsas unlike the Saarland which the french also tried annexing after WW1 and 2, didnt show major resistance to being integrated into france. These regions are right next to each other and had about the same percentage of germans, yet the desire to rejoin germany was massively apart.

Another factor that leads to bigger regional devides is geography. Italy is very mountanous. The po valley is the only continous chunk of properly usable land for mass industry, with the rest being scattered down the boot, all cut apart by pretty extreme mountain ranges, for an industrialising nation. We see it in Afghanistan, Iran/Persia, China, Spain, anywhere to mountanous basically, that regions are culturally and economically more seperated. Meanwhile all of north germany, 2/3rds of the empire was on the european flatland connected by the rhine to the south west. meaning this area is very easily traversable and not easily geographically ripped apart. The part of germany this applies the least for is Bavaria and fittingly its the most distinct part of germany, being closer to austrian dialect then a vast majority of germany.

Italys divide is north to south. The richer far more industries north seperating itself from the more rural south, economically and historically. While the seperation partys are very unlikely to win, they have a better chance at succeding then most other partys promoting breakaway nations in europe.

Germany usually also has a north south divide, protestant and flat north, vs catholic, mountainous south, though this changed with the cold war. Artifically, the biggest difference is now between west and east. One far poorer and linguisticly different with a very noticable way of speaking. This slowly fades away since the decades of reunification as generations pass, but it shows how man made circumstances can also create a divide that shouldnt usually be there. Same with austria, for as long as german is a concept its obvious austria belongs in there, yet WW1 and 2 lead to a seperation, which lead to austrians to no longer be seen as just yet another group of germans, like saxons or bavarians. They speak the same language, plenty of TV broadcasts are used for both nations, as both understand it, they are tied together throghout 95% of their history, yet these days saying austrian is german feels just a bit to brown to mention in public. Again, man made distinctions in cultural regions.

So, back to Italy and Germany. I think the difference in unifying regional cultures wasnt as big as you may think, and the advantage that was there by the germans, can be mainly lead to industrialisation and prosperity. Things like railways made the world smaller, and the more there are, the closer the people a state over feel to you. Making your country, feel like one big natural region, instead of a bunch of seperate ones artificially strung together.