Qwiss I'd argue that Havertz at the 9 ties up defenses, albeit in a somewhat more unpredictable manner with his movement between the lines and then dropping deep. He's not going to physically pin back the CB's as consistently as Haaland does, so I do see your point there about creating that space but he does create a ton of space both for himself and for others around him. We do need our midfielders to start getting better at taking advantage of that space to pop up for goal opportunities this year.
I think if we can just get some more reliable production from the left side (Martinelli/Merino/Calafiori) this year, the need for an out and out finisher at the 9 becomes far lower. As has been stated on this thread, we only finished 5 goals behind City for the season despite getting only a combined 10 goals from Jesus/Martinelli. That's a 16 goal drop from the previous season so even just getting them closer to 20 combined goals would be a huge improvement without asking for any additional improvement from other players. I don't think that's too much to ask. However, if we could also add another forward with the potential ability to contribute 10 goals, we are looking at 100+ league goals without even asking for players like Saka, Havertz, Odegaard and Rice to increase their output (which I also think they can do). Add in Eze and Merino to this team and I think we will be scoring for fun this year while also positioning ourselves for a marquee 9 next summer (Isak/Sesko).