I agree with you partly on execution in general and totally on using nitrogen.
My ONLY concern about application of the death penalty is the wide spread incompetence of “lawyers” in the courtroom, most particularly judges.
And over enthusiastic detectives and prosecutors withholding evidence. I believe in capital punishment under special circumstances when guilt is proved beyond a shadow of a doubt. With the decades of expensive appeals these guys get, it makes more sense to give some of them life.