That measurement fed a computer model, but if I'm reading the article right, most of the work was actually based on wartime records on heavy water and graphite. Anyway, the model showed they would have needed twice the uranium and heavy water they actually had.
I don’t know whether it would have made a difference (it isn’t trivial to determine that from this article or the paper), but they had more uranium than they knew they had. https://pure.rug.nl/ws/portalfiles/portal/735593238/36_1_onl...:
“De Haas, one of the directors of the Kamerlingh Onnes Laboratory at Leiden University, quickly realized the strategic value of uranium and sprang into action. He used his close government contacts to persuade the Dutch prime minister, Hendrik Colijn, to immediately order a large amount of uranium from the Belgian firm Union Minière du Haut-Katanga, which mined deposits in the Belgian Congo.
The Dutch placed their uranium order just a few weeks before Joliot-Curie made Union Minière aware of uranium’s new potential. When 200 50-kilogram barrels of yellowcake—a form of uranium oxide—arrived at his laboratory in Leiden, De Haas initially had them stored in his laboratory. But the uranium increased radiation levels and interfered with measurements, so the barrels were moved to a locked room in a basement at the Delft University of Technology. Remarkably, they remained undisturbed in the basement during the war, undiscovered by the German occupiers.”
Its also suspected Heisenberg didn't want the design to work (its the given reason why he wasn't killed by Berg). But it was still a reasonable possibility during the war that the Germans could have made it work.
It is very upsetting that one of the most profound minds of 20th century and Germany, entirely in the tradition of Leibniz, Goethe, et al., is blackwashed because of the coincidence of existing during the Nazi regime.
(https://northtownbooks.com/book/9783030256951 << Recommended)
Phew, that underground mission was more important than I thought!