True, alas.
The F1 engine on which the Saturn V relied was actually around in the 1950s, built to deliver Ed Teller’s H-bomb, which also gave us the B-52; Teller’s design worked, but was superseded by smaller designs. Von Braun took the F1 with him, all the while intending it for a lunar program.
F1B .
My father worked at Redstone Arsenal (from the mid 60s to the early 80s) and knew many of the these German scientists including Von Braun. Dad always said they were brilliant and happy as hell to be Americans.