Genoa-born filmmaker Enrico Casarosa may have left Italy over two decades ago, but he has been continually drawn to and inspired by his home country. Both his Oscar-nominated short “La Luna” and his latest feature “Luca,” available Friday on Disney+, are unabashed love letters to Italy. “Luca” was inspired by his own childhood friend Alberto, who was more confident and adventurous than Casarosa. He even named the character Alberto, but there’s one major difference: In “Luca,” the boys are sea monsters who outside of water can pass as teenage humans. Jack Dylan Grazer, who voices Alberto, recorded his dialogue from his mother’s closet.