Instead of being executed for their crimes, the convicted Nazis should have been kept naked except for a loincloth in a narrow but long cage that was concrete on all sides except for a metal door locked at all times that they would enter into initially, and metal bars on the ceiling. The reason for this is they'd be displayed to the public to shame them and make their lives a living Hell. Visitors would be allowed to spit, piss, or even shit down into the cell, maybe even making a game of trying to hit the Nazi with a big old turd. (Or alternatively, make the Nazi dance for a bit of food.) The Nazi in their cell (only one Nazi to a cell of course) would only be let out for medical reasons, since we'd need to keep them alive to suffer longer, since this world is the only world we have, the afterlife is a delusion, and killing a Nazi is far more humane than they deserve.

Such a punishment for hate crimes would of course extend also to individuals in the modern era who are convicted of hate crimes. I know a lot of trans people who would love to be able to take part in publicly shaming transphobic murderers this way. Maybe even include mass shooters, terrorists (including the white variety), and serial killers too. You could fund prisons just on the tourism money alone!