Unit on both sites are drawing board, partially developed, or fully developed naval and air units. The LZ-135 was never built, only drafted on paper and in this sense it was real.
A fair point, though it should be remembered that some on-the-drawing-board concepts are less real than others. Germany’s proposed H-Class battleships began as realistic designs in 1938 or 1939, and one or two of them were actually laid down. When the construction work was suspended, however, drawing-board work continued on-and-off until 1944. The design kept getting upgraded, and kept getting more and more unrealistic; from about 1941 onward, these designs can be regarded as purely paper studies, with zero chance of being built and thus little need to keep practicalities into account. But at least they were being designed by competent naval architects, in contrast with Hitler’s propensity for sketching battleship designs on the back of envelopes. (This fondness was an odd one, in view of his land-warfare orientation, but wasn’t entirely out of character: he believed that he knew more about warfare than his professionally-trained generals, and he similarly felt that he could come up with better battleship designs than professional naval architects.) Hitler once proposed building a battleship armed with 800mm guns of the Gustav / Dora railway artillery type; in a rare example of common sense winning over Hitler’s fondness for gigantism (as illustrated by the 188-tonne Maus tank), an admiral managed to talk him out of the idea by pointing out that no existing German harbour was large enough to accommodate a ship big enough to carry guns of that size.