Documenting this for future reference.
Singpass setup for new users broke at some point since Android 17 release of GrapheneOS. Existing users can still continue with their install and refrain from deleting the app as far as possible.
Facial verification fails with 88 FV17 error code.
Template reply unchanged from 2025.
"To ensure consistent standards of security, reliability, and protection for all users across millions of devices, the Singpass app requires platform-level certifications, including Google Play Protect certification. Devices that do not meet these requirements, such as those running custom ROMs like GrapheneOS, are not supported."