There had been discussion on the Github issue tracker (https://github.com/GrapheneOS/os-issue-tracker/issues/3795) of having a primary passphrase for first decryption, then a shorter secondary PIN for subsequent screen unlocks. I know this has been implemented for a secondary fingerprint unlock after primary passphrase, but the GH issues for a secondary PIN and secondary fingerprint unlocks seem to have been conflated.
Did a secondary PIN option ever actually get implemented, or is fingerprint the only option for secondary unlock?