> “Under German law scanning books – regardless of the purpose – would not be permissible and constitute a clear violation of copyright law,”
Excuse me, what?
https://law.stackexchange.com/a/93882
"Individual reproductions of a work by a natural person for private use on any medium are permitted, provided they are not used directly or indirectly for commercial purposes …"
German copyright law has no Fair Use. There are copyright exemptions for private or academic use, but commercial use has no such exemption. Books have special protection even according to § 53 (4) b).
And yes, it's the duplication which is illegal, not the publication of them.
[1]: https://www.gesetze-im-internet.de/urhg/__53.html