Kevin,
The Weimar Republic was a democracy but took over a lot of restrictive laws from the Kaiserreich. Conversely, the regime after 1933 turned quickly to a dictatorship but in terms of amateur radio gave a bit more access. Compared to other western countries, the number of legal stations was still dismally low. Some people say the regime recognized the value of ham radio for propaganda, I think they just realized the unimportance of keeping the Prussian Telegraphengesetz in place. Anyway, the period after 1933 needs no coverage, the call signs during these years are listed in the US callbooks, (besides the few Kriegsgenehmigungen, but the list is also available online).
Best, Fritz