Yeah, “pie” as a way to describe a pizza is almost as old as American pizza itself. There are a few good write ups on the origins of it:
Why Is Pizza Called Pie? All About The Other Name For Pizza - Crust Kingdom
But in short, Italian immigrants were referring to “tomato pies” over 100 years ago. My great grandparents, who were both born in New Haven in 1916 called them that since they were born. Their parents arrived there a few years before that from Italy, not sure if they would have used the word since English wasn’t their native language.
‘Za, on the other hand, is a ridiculous term that best describes pizza acquired from a mall food court.