Well, i actually do not think City were unlucky, Liverpool were obviously the better side and they deserved the victory that they got, but i am pretty sure Pep and his boys would not think about this one too much, they will just take it as a mere pre-season game, shake off the loss and go about their business of winning games in the EPL, when it starts this weekend.
Liverpool played better and won it. Manchester City did not control too much ball and created too many opportunities like two matches between them in the past season. I think Manchester City still need time to adjust their tactic to use Haaland. Haaland has some bad finishes in that match too.
Haaland had about three good chances to score that day, but he could not just stick the ball in the net, i know he will feel a little bit bad and it might affect his confidence a little because two of those chances were pretty much him and a gaping goal, so it was even harder to miss than score, well the City camp know how to get their groove back, so i am pretty sure Pep and the team will help Haaland forget about that day and focus on more important titles and games coming up. City still remain my favorite to win the league this season.
Give him time. Missing a few opportunities in a first official match for a new club is not the end. Haaland is very strong and he will score goals again. He has an excellent career from Malmo, Salzburg to Dortmund and will continue it in Manchester City and Premier League.
Haaland did not have good connections with other players in Manchester City but time will help him to improve it. Manchester City has many smart midfielders and they can provide good key passes to Haaland. They just need more time to find each other and play better together.