I struggle to imagine JK Rowling resisting the rise of the Nazis if she was a prominent figure during that time.
She would be far more likely to write an offshoot Harry Potter book about a nice Hitler Youth Camp where a noble and pure blonde hair blued eyed boy took the heroic choice of not attending Wizard School even though he was a wizard in order to support his country and join the Hitler Youth. Antics ensue in this fun and lighthearted romp through racial purity after a secret cabal of jews infilitrate Hogwarts to sabotage it and the perfect white boy must save the Wizard School with his newly found friends!