Very interesting, thanks much.
The greatest book I've ever read on the entire subject is The Making of the Bomb by Richard Rhodes. About 900 pages, very dense (including many dozens of pages on theoretical physics and the like that eclipsed my understanding), the 1988 Pulitzer Prize winner.
It's not just about the Manhattan Project. It's a study of the history and politics and scientific development of the entire 20th century.
Heavy, heavy duty, but a must read!