I dunno, I read Richard Rhodes' The Making of The Atom Bomb and he said nothing like this.
If this is true the Nazis had the beginnings of an implosion device, and they tried an open air test near Berlin?
Or had a serious criticality accident, also near Berlin?
Rhodes was right. This crude device was a dirty bomb, and would not initiate a fission reaction. Calling it a 'nuclear device' is ignorant or deceitful.