The Government Printing Office API What's Available site links to the Congressional Directory, but the most recent CD available appears to be the 115th (2017-2018). Does anybody know if this is intended behavior, or if there is another GPO collection that contains listings for the 116th Congress (2019-2020)?
For Future Reference
Posed this question as an Issue on the GPO GitHub repo, got this as an answer:
This has not been added to the system yet. Once the volume has been printed, it will also be added to govinfo and made available via the API.
The U.S. Code section indicates that this is to be printed and distributed "as early as practicable". My understanding is that information is still being compiled.
The first edition of the CDIR for the 115th Congress was made available in June 2018.