"... still had an
effective Atomic Bomb program until December 1944."
Not ??
IIRC, they had a bunch of different projects, but their physics was off. IIRC, their 'pile' moderators were not pure enough. Also, they were verrrry slowwwwly separating their U isotopes with what seems a Calutron, an industrial-strength mass spectrometer.
https://en.wikipedia.org/wiki/Calutron
Upside, it works.
Downside, they would need a lot longer than they had...
Best, IMHO, they could get would be low-end enrichment, a gun-type bomb with a seriously dirty fizzle. And, with a weight far beyond V2's throw, they'd have to deliver by submarine or bury as a monster mine...
OT: I can't find a 'strike-through' to go with italic, underline etc...