Please note that you can be ISO 27001 certified by any organization recognized as a certification body by an accreditation body. In Germany, the accreditation body is the German National Accreditation Body (Deutsche Akkreditierungsstelle, DAkkS).
From this DAkkS site (https://www.dakks.de/en/content/accredited-bodies-dakks) you can find German certification bodies for ISO 27001.
This search result (https://www.dakks.de/en/content/accredited-bodies-dakks) provided 9 certification bodies in Germany (TÜV SÜD, SGS-TÜV, and DQS among others). Please note that TÜV is a designation, not the name of an organization, i.e., not all organizations named TÜV are related or part of a bigger company.
This article can provide you further information about certification bodies:
- How to choose a certification body https://advisera.com/blog/2021/01/11/how-to-choose-an-iso-certification-body/