A common complaint of heart attack victims is "I can't breathe".
The best position for such a person, especially one who is intoxicated, is on the side.
I think they're going to have a very difficult time proving that anything this cop did contributed to Floyd's death.
Not that it matters.
Guilt or innocence is irrelevant.
The die has already been cast.
Well, there is some objective evidence to show that not much pressure was being applied: Floyd continued to talk, and remained conscious for quite a while. If significant pressure had been applied to the carotid, he would have passed out in 15-30 seconds max.
This is not going to be a slam-dunk to prosecute.