The PRF extension in the context of WebAuthn does not specifically mention biometric authentication. The extension primarily focuses on utilizing security keys (physical devices) and generating pseudo-random functions (PRFs) for encryption purposes.
PRF could be implemented for encryption purposes following the biometric authentication process in Passbolt to unlock the vault.
However, you will still need the native Biometry Support (Mac Touch ID, Face ID/ Windows Hello Fingerprint, Face)
As a Windows and Mac user myself, I am also excited to see advancements in Safari and the Mac desktop environment.
Having a desktop app as a vault for every browser extension seems like a robust security architecture.
The idea has won me over!