I've read that the children that were raised to be Nazi's were the most ardent and sadistic. They fought to the end. I have a picture of a teen guard at Buchenwald that was strangled to death by the inmates on the day of, or before, the liberation. It is both chilling and sad.
Taika Waititi a pretty safe pair of comedy hands. Cheerfully recommend his 'What We Do In The Shadows', and he bought some joy to the often leaden Marvel stuff in Thor. I may even go to the cinema for this.
If you can make a bizarre comedy about Joseph Stalin I don't see why you can't make one about Hitler.
Yes, the young ones were often the worst. Nazism was a young person's movement to a large degree; Hitler was 43 when he took power, young by the standards of German politics. Young people like to join in groups of like-minded kids (that's why they join street gangs), they can be aroused by idealistic causes, they like to test themselves physically, they like the spirit of adventure, and boys at least like to play soldier. Young people often enjoy violence, too, which suited the Nazi ethos. The 12th SS Panzer Division was recruited in part from the HJ, and it had a repulsive record of atrocity throughout its existence.
I've seen the trailer a couple of tomes now and was struck by a line of dialog where the Jewish girl says the boy is not really a Nazi, just someone who likes to dress up and be psrt of a group. Makes me wonder if the film might have a deeper meaning wrapped up in a parody?