According to the New York Post, if the Sabres retain $5 million of his salary, the Rangers would be so kind as to add Kakko to be the “centerpiece” of the deal.
https://www.google.com/amp/s/nypost.com/2021/07/31/kaapo-kakko-may-be-rangers-key-to-jack-eichel-sweepstakes/amp/
I would imagine that if the Sabres were willing to retain half of his salary, more than half the teams in the league would be interested in making offers