Nunez may not even be remotely close to Haaland, but I agree that the team plays a big role in there. If Nunez played for City and Haaland played for Liverpool, I think we would see Haaland score less and Nunez score more. Would Haaland still score more than Nunez? Maybe, maybe not.
I think the teams involved does play a huge role here. Nunez is a very talented player as well and could very well be relied upon to score goals. Manchester City plays beautiful football as a team and does a pretty good job of getting the ball over to Haaland who then goes ahead to score goals.
I agree with you that if the roles were reversed and Darwin Nunez was playing for Manchester City, we would see Nunez score more goals and Haaland score less. I think the entire team hugely contributed to a very successful first premier league season for Haaland.