3rd degree murder in Minnesota requires "depraved indifference" -- but in Minnesota that term (as described in earlier MN Supreme Court Cases) means more or less, heedless of the danger to the public at large, and specifically NOT reckless towards one specific individual.
I think they can/should nail Mr. Kneecap for not even going through the motions of CPR, when another policeman said that George Floyd didn't have a pulse. But that'd be another set of laws.
It required "...an act eminently dangerous to others and evincing a depraved mind, without regard for human life..." A much lower threshold than what you describe and one which seems to describe Chauvin's actions. Noor was convicted of it, it seems likely that if Chauvin is convicted of anything it'll be third degree murder as well.