Italian here and...yeah, it didn't make any sense even for me. So i found the source and the artist only wanted to draw something with the same shape of the region, so for example sicily is a slice of pizza because it has the shape of a slice of pizza, no other meaning.
The source is on reddit, here's the link: Map-Art on Reddit
Edit: I wrote Campania instead of Sicily
Era tardi e non mi sono accorto della gaffe, ho corretto