The sheer economic costs of the manhattan project were prohibitive to a nation like Germany, even if they'd managed to build a functional project team.
(how many nations had 14,700 tons of silver lying around)
I don't believe the silver was strictly necessary. Copper windings would have worked for the calutron. Silver was used because copper was not as easily available at the time. But the point is valid. The project was originally British, moved to the US for economic reasons.
The silver bus bars in the magnetic separators were kind of a stunt, if that's what you're thinking of.
A nation like Germany on the cusp of losing a war sure. The opposite scenario of Germany controlling all the resources of Europe and Africa is a scary proposition.