Public authorities made a page that gathers all the different options you have:

Bundesverband Deutsche Startups - SARS-CoV-2/COVID-19 - Collection of Startup Best Practices

Initiative by the German Government for startups, helping them get loans for prolonged runway:

ERP-Gründerkredit - Universell (073, 074, 075, 076)

Overview of the city of Berlin helping startups get loans:

Corona-Virus: Anträge auf Liquiditätshilfen ab morgen online möglich