Obviously Max Schmeling was a notable German boxer from the Nazi period, but what others were there? Did any other German fighters find similar success during this time?
They had a championship called the "German BDB championship." You can get an idea of what the Nazi boxing scene was like by tracking that belt.
Quickly looking through here so there may be more, but here are the men of German nationality that were ranked by Ring during that period of time Max Schmeling at heavyweight Walter Neusel at heavyweight Erich Seelig at middleweight Gustav Eder at welterweight Adolf Heuser, not sure which division but it's somewhere middleweight or above I can't recall any notable German boxers below welterweight during that time period.
Doing some research on Gustav Eder and wow, very interesting fighter. He even fought for a world title in 1938 (atleast, I think the IBU counts as a title) and lost by SD. It's crazy Nazi Germany could've had 2 world champions that year