Biometrics like fingerprint (Windows Hello,PIN) isn't a very secure replacement for the Primary Password because the PP encrypts the passwords stored in logins.json in the profile folder and thus gives better protection. Biometrics can be used instead of the PP and this means that the passwords aren't encrypted and having access to the profile folder is sufficient to access the passwords. Note that this is also the case if you unlock the passwords via the PP during a session. Firefox does support this Biometrics feature, but it hasn't been enabled. *https://support.mozilla.org/en-US/kb/lockwise-password-authentication-prompt