You can't say, "I can't breath" without breathing. Just try it. It is a physical impossibility. Air must be going through the vocal chords for them to work.

Floyd  did not suffocate, he was talking (you can't say "I can't breath" without breathing) up until the moment his damaged heart, further impacted by massive doses of meth and fentanyl, gave out from stress, likely the stress of his resisting arrest.