There's pretty much a blanket ban on Americans right now unless you have a student visa or a pressing need.

This bit (from https://www.bmi.bund.de/SharedDocs/faqs/EN/topics/civil-protection/coronavirus/travel-restrictions-border-control/travel-restriction-border-control-list.html#f13919566) applies to my situation:

Self-employed and dependently employed business travellers who carry out activities referred to in section 16 no. 2 of the Ordinance on the Employment of Foreigners may enter Germany under this category of exemption if they meet all of the criteria for doing so. However, they must provide sufficient evidence (e.g. by presenting documentation from the employer or business partner in Germany) that their entry is absolutely necessary even taking the pandemic into account. A declaration of the absolute necessity of business travel signed by the employer or business partner in Germany can be used to provide sufficient evidence. A declaration by an employer or business partner in the traveller’s country of origin (non-EU country) is not sufficient on its own.