Was Nimitz carrying nuclear weapons? Could 1940s technology reverse engineer one? Granted the Nimitz would have been carrying very advanced thermonuclear weapons, but basic designs for that type were only ten years out. A lot of the fundamental science had already been done. Working examples could have sped things up a lot, how much? Unclear. What about the input of people who knew what nuclear weapons would unleash on the world?
What about the aircraft? Even if exact clones didn’t happen, they likely would have vastly accelerated the deployment of combat jets and helicopters. Hell, even if the Allies only reached Sabrejet equivalents, if they beat the Germans the Luftwaffe would have been done in a matter of weeks. What about guided missiles? Again, exact clones might be unlikely but even a primitive Sidewinder would be a game changer. Or hell, even a Vulcan cannon for aircraft and ground use would be a devastating weapon in the 40s. And someone might suggest the idea of going to 30mm like the A10s Avenger cannon.
Small arms? The M16s the Marine detachment carried should be cloneable with 40s tech with support from qualified armorers and working copies to reverse engineer. Yes, they are smaller rounds than typical combat rifles of the era, but they are still quite lethal and you can carry far more of them. And the M60(did carrier detachments have any?) might have been adaptable to 40s ammunition to simplify fielding what would have been a gamechanger of a medium machine gun.
And the tactical development could have been tremendous, even aside from the vast intelligence advantage Nimitz officers could have given the Allies about Axis war plans and capabilities.