Not able to answer that question but the Auskunftspflicht also covers police surveillance footage.

Personal anecdote: I was involved in a student demonstration once that ended with the police recording every individual separately in addition to checking our national ID cards. After about 14 days I wrote them a letter requesting information about what data they had kept and to destroy that data if it is not part of an active investigation.

I received a formal response saying they had already destroyed the data shortly after collecting it because they didn't end up needing it.

I presume the law is exactly the same as with any other organisation, i.e. the BDSG (Bundesdatenschutzgesetz) which as of now implements the GDPR (DSGVO) in Germany.

Yes, and meanwhile they illegally sniff your whole Internet traffic... just one current example https://blog.fefe.de/?ts=a5f2e96c

Generally, Bundesdatenschutzgesetz (BDSG), mainly Kapitel 3. §57, §58 and §61.