No, I don't think so; not only is the material different, but also its construction. This is a piece of blue (not hellblau) coarse material with a self-edge, with the two corners at the top folded over and sewn to the back to form the "point" of the shoulder strap, i.e. there is no backing. It is also much thinner and more flexible than a normal shoulder strap.
I don't know why they're so hard to find, there must have been millions, but maybe they're not easily recognized as shoulder straps, or anything military, and thrown away over the years / not put up for sale?