The young Dutch striker is good at playing in the wing and spear positions, which makes him a distinguished alternative to the Norwegian striker Erling Haaland as well, who may leave during the current summer transfer season,
Borussia Dortmund are preparing for the unforeseen, they already have good wingers who can easily cover up the Sancho I think that was the reason they bought T. Hazard last season they knew Man utd would not give up on Sancho and that's the same dilemma they are facing now with Halaand they know he is a top priority to Chelsea this season and they are going to do anything to get him and Halaand is also open to a move so they needed to get someone should in case the Halaand deal go through. Malin is a promising young player who can play ST and CF.
Chelsea are preparing an improved £130m according to several reports, they have a good squad they just need a clinical finisher to contest for the league.
I don't think that the problem is the first squad they still have even after Sancho left. I think that the bigger problem is a long and demanding season with injuries. That is why Bayern was always so strong. When somebody was injured from the first squad, the substitute could easily compete on world class level. I don't see that for Dortmund if they let two or three world class players from their first squad go.