I think the floor of the window will likely be close to what RowJimmy predicted (Kroupi & Bouaddi) and even that would be a solid window for me. I think the ceiling would be Klaus (Kroupi, Kvara, Tonali), which would be an absolutely ludicrous window that would make us instant favorites to win everything and likely run away with the league. Even the second options in that post (Gordon/Barcola, Alvarez/Yildiz, Fernandes/Reijnders, Kayode) would be an insane window.
I think if we do what everyone is assuming we will do in selling Jesus, one of Trossard/Martinelli, and Norgaard then signing 2-3 players will be a good window. You can continue to address things in a one in/one out fashion if White were to leave.
As long as we bring in a top level attacker this summer at the very least, I will be happy. I think my more realistic wishlist is likely Barcola, Kroupi, Fernandes, Acheampong (if White leaves). Exciting times!