The equivalent to section 230 would be Section 10 Telemediengesetz, but from my own experience law enforcement here seizes first and asks questions later for anyone that's not a household name.
NetzDG is much less broad, only applying to social networks (so not Telegram) with more than 2M users.
Why is Telegram not a social network? What's the key differences between a social network, a forum and a messenger service (with groups) that we could define to figure out what telegram actually is?
well, let's check section 1, paragraph 1-3 of NetzDG
>(1) Dieses Gesetz gilt für Telemediendiensteanbieter, die mit Gewinnerzielungsabsicht Plattformen im Internet betreiben, die dazu bestimmt sind, dass Nutzer beliebige Inhalte mit anderen Nutzern teilen oder der Öffentlichkeit zugänglich machen (soziale Netzwerke).
We have a requirement for profit motive (so the Fediverse is mostly safe) and sharing arbitrary content with different users (broadly) or the public.
>(2) Plattformen mit journalistisch-redaktionell gestalteten Angeboten, die vom Diensteanbieter selbst verantwortet werden, gelten nicht als soziale Netzwerke im Sinne dieses Gesetzes.
Blogs and news sites that do not claim the above-mentioned protection under TMG are specifically excluded as social networks here.
>(3) Das Gleiche gilt für Plattformen, die zur Individualkommunikation oder zur Verbreitung spezifischer Inhalte bestimmt sind.
Further exceptions for "individual communication" and "posting specific content".
So I guess a Telegram Group specifically counts as a social network under this definition. It'd be anyone's guess how many people a group needs to no longer count as "individual communication", that's probably for a German court to decide.
NetzDG is much less broad, only applying to social networks (so not Telegram) with more than 2M users.