Yeah, I grew up in PA and that's pretty common there, but when talking to one person, it's usually "Hey dude" or "Hey man" (also mostly gender-agnostic)
Only that one guy would use it for one person, sometimes similar to whatchamacallit: "Guy! Whaddareya doin up there?!" "C'mon, guy! We're gonna be late!" "Any of you guys see my toolbox? Did guy take it again?" (Which guy, man? Dude, there's like ten guys here. Bro, you gotta be more specific.)
Only that one guy would use it for one person, sometimes similar to whatchamacallit: "Guy! Whaddareya doin up there?!" "C'mon, guy! We're gonna be late!" "Any of you guys see my toolbox? Did guy take it again?" (Which guy, man? Dude, there's like ten guys here. Bro, you gotta be more specific.)