Incidentally Mein Kampf often is available in libraries in Germany (in a commented version, here for example https://www.provinzialbibliothek-amberg.de/discovery/fulldis...), and was never banned in the sense that people understand banned. You could always own and sell old versions however, printing and distributing new uncommented versions could be deemed Volksverhetzung.

It's also a crappy text and definitely not necessary to understand WWII, there are better texts.