The focus is undeniably on the Corleone family, the men of which are the protagonists. Of course the movies offer deep social commentary - as does Sopranos - but in City of God, the protagonist and the focus of the film is the favela, whose story is narrated by Rocket. Rocket is not the protagonist, neither is Zé, Knockout Ned, and whoever else. Just as in The Wire, the focus and the protagonist is the city of Baltimore, not Avon, Marlo, Stringer, or any of the cops.
You can't identify a concrete community focus like that for Godfather, only an abstraction and allegory for the broader Italian American experience. shyt the second movie takes place in Nevada and Cuba as much as it does New York; and even in the first movie time is divided between Sicily and New York.
If you leave the favela in City of God, you're irrelevant to the story from that point forwards. Shaggy and Benny both die as they are about to leave, which symbolises the inescapable, prison-like nature of the favela. Even Rocket, the only guy who gets out alive, has to go back in.