the director of the ciao alberto! short and the story lead on luca mckenna jean (@kennnajean on insta) posted some of their luca and alberto fanart on their story!
Many people noticed that Giulia has similar clothes to Tombo from Kiki's Delivery Service
But Luca and Alberto also have outfits, strikingly similar to those of Conan from old Ghibli cartoon Future Boy Conan!
In most concept art, Luca is wearing white shirt, more closely resembling the one that Conan wore for some time
But in the movie, it has blue stripes, more similar to the one that on Fio
It was confirmed that towns name Portorosso - is a reference to Porco Rosso (It was also a second name of Luca in early concepts)
Could Luca's shirt be another Porco Rosso reference?
In my opinion, Future Boy Conan must've had a huge inspiration on Alberto character, not only his design, but also behavior, lifestyle and houses very similar!