The Nazis spent so much time, money, manpower and raw materials on goofy sci-fi stuff that they hurt their production of regular armaments. A lot of their drawing board stuff didn’t come to fruition for decades after the war, and a lot of their research is still being used.
Wasn’t one of their top priorities Global Warming?
Much of this stuff was just lines-on-paper, meaning no serious effort was made to bring this stuff online. Propulsion, electronics & material science weren't up to the task. It's like Leonardo DaVinci's drawing of a crude tank - so what? If you don't have the materials that are strong & light enough to build one, and if you don't have precision machining to build the drive mechanism, then it's all pie-in-the-sky.