re: At full strength who was more powerful in ww2 Germany or US?

No one in the world had any idea how massively powerful the American industrial machine was. The Americans built 175 Fletcher class destroyers during the war. Not destroyers. 175 of just one type of destroyer. That doesn’t count the hundreds of amphibs, transport, minesweeping, auxiliary support ship, etc. before you even get to the hundreds of actual combatants. Now extrapolate that kind of production to tanks, trucks, airplanes of all types and the US could probably outproduce all the other combatants in the war combined.
Add to that the technical and scientific prowess and no one could come close to competing with the US.