#3 seems to have that look of inevitability on his face. I can't imagine Chauvin in particular would survive general pop very long at all. I don't particularly agree with how the US penal system seems to work anyway, you might as well give the guy the death sentence if he isn't going to be sent somewhere segregated, but the issue goes much deeper than that.
The other thing about this that bugs me is the practice of putting your knee into the neck of a person - to me that is mis-training, or at least an unacceptably grey area which needs eradicating quickly. When someone is cuffed and on their stomach if you kneel on the head then yes it is uncomfortable (you're being arrested after all, not tickled) but there is little risk of suffocation. Even the upper back. The idea being to stop the person lifting their head and upper body to move. This kneeling on the neck is the kind of asshole, I-used-to-be-a-school-bully bs you expect from a percentage of cops.
I presume these guys are trained in methods, but perhaps take a leaf out of martial arts practices and make the methods standard at a federal level downwards.