Ole has nothing to do with it. Hes the manager. All the stuff with agents is handled by judge and woodward.
Active negotiations yes, but persuading the player to believe in the project of the club is very much down to the manager.
I doubt they are actually negotiating on this PR-tour. They are just meeting with clubs to inform them of what level they are looking for in regards to financial package, assurances from the club in regards to ambition/play-time etc., the interest of the player to move this year (probably depending on how Dortmund's season ends) or next year or potentially staying even another year if Rose makes Dortmund challenge for titles (since this potentially also informs of the players interest to stay at the next club for a while or keep moving around) and then whatever other info might be interesting like what jersey number(s) Haaland wants or whatnot. Probably also informing of the price Dortmund has set for him this summer and all the details surrounding his buyout clause if they don't already know.
Actual negotiation for terms cannot happen before Dortmund allows it, usually after the club has a bid accepted, but with a buyout clause in a year this is just a formality (and I'm even theorizing the clause might activate early this summer if they fail to qualify for CL).
The clubs may inform of their interest to bid for the player and give a general sales pitch of what makes their club/project great.
Ole can easily get most of this info conveyed directly between himself and Haaland senior on a call. When actual negotiation starts later it will go to Raiola and Judge (with probably Murtough, Fletcher and Haaland senior sitting in at the meeting).