NoKeyringError after install in Pydroid 3

After "pip install keyring" with no errors calls to keyring.set_password or keyring.set_password raise a NoKeyringError exception.
So it seems there is no backend installed. Should this not have happened when installing keyring or at least been flagged?
Which backend should be installed on Android (10) using Pydroid 3 (Python 3.8)? How?

Start by reproducing the NoKeyringError after installing keyring in Pydroid 3 on Android 10 with Python 3.8. Investigate how keyring selects or reports an available backend in this environment; done means the expected backend behavior is fixed or clearly documented for Android users.

Written by the indexing model from the issue text.