It's not that I dont think Bayern wouldn't try, nor that he would not go on principle or something, I just think he wants to show career progression and a kind of momentum. Moving to Bayern doesn't make as much sense if you see his context as becoming the worlds best striker. He backs himself as a player, and if he goes to Bayern that means he would have spent 8 years in one league, and he would be leaving Bayern in his mid 20s. I think Haaland would not want to be seen that way, maybe if Bayern were willing to give a 5 year contract with say a £100m sale clause after 3 years you might see him move there, but I don't think Bayern would entertain that.
Genuinely think this lad wants to show himself to be the best and I think he would consider a move to either the PL or La Liga, followed by a move to the other country after. From a timing POV I think it would make more sense to currently go to the PL next year, as la Liga is in a bit of a lull, as are RM. Stay in the PL for 4/5 years before moving on.
I think if he wants to guarantee a move on he would be better picking United rather than City, getting out of City is I think more difficult than leaving United. I have no doubt that if he joins us he would want to leave in 4/5 years to showcase himself in la Liga. I do think we will start to see lots more players doing things like this, especially elite level players.