The German state railway company sells their used trains here: https://www.db-gebrauchtzug.de/

I am somewhat sure that it was codeberg but not 100%. As of now they are definitely searching. I’ll edit my comment to avoid confusions.

My last info with CodeBerg and donations was that they had funding for the next years and recommended to donate to some other projects. Ist that still valid? Or am I remembering wrong?

As of now they are definitely looking for donations, so please consider supporting them.