There's a merged pull request on the void-packages repository

New package: pam-gnupg-git-20191206
https://github.com/void-linux/void-packages/pull/18335

Description:
This template adds support for the pam-gnupg PAM module, which presets key passphrases in gnupg2 to the PAM authentication passphrase. Configuring PAM to load for authentication after the pam_unix module and session management after any elogind or ConsoleKit2 modules will pass the user's password through gpg-connect-agent to preset the passphrase; as a side effect, gpg-agent will be launched if it is not already running.

The template references a specific git commit, which is not allowed according to CONTRIBUTING.md; I'm hoping an exception can be made because the module author has not published specific releases but the module is very useful.