I think the Knicks would only be interested in Middleton if they thought they could get Giannis also otherwise I don't see the Knicks being all that interested. The Knicks are probably the favorites to get Giannis if Giannis wants out as they have the picks to offer the Bucks. The Knicks have 1 '23 1st round pick from the Mavericks and 3 first round picks in '24 with one of them being their own. So if the Bucks want three first round picks they could take all of the Knicks 1st round picks in '24. You are looking at two possible lottery picks with the Pistons and Wizards '24 1st round picks.
Something like Randle, Robinson, and the three '24 1st round picks for Giannis. I don't think the Bucks should or would do this but I think that is close to what could be expected for a Giannis trade.
I would rather get back Powell and Morris for Middleton than take on Kawhi. I don't think Kawhi is even interested in playing basketball anymore. He won his championship and got paid I don't think he would put in the time to get better. I think Kawhi would be extremely toxic for the Bucks.