https://www.ateliertuffery.com/

The sizes are somewhat odd, but send an e-mail and ask, they reply swiftly.

https://lichtfuchs.de/
https://hellum.de/Made-in-Germany

As Christmas lights seem to becoming a one-time-use product, I was looking out for longer lasting ones and found to brands made in Germany, but it is not the whole range that is made in Germany, I understand.