give https://passkeys.guru/ a try and see how it works compared to what you know
Where do I see what permissions I just granted from my (naturally, dummy) gmail account? What happens next time I want to login?
the only thing shared with passkeys.guru is the pubic key of your device (which was generated specifically for passkeys.guru and cannot be used to identify you or your device on other websites)
no biometrics or any other PII was shared with passkeys.guru in the process.
technically, you can use any identifier you want with passkeys, even just a dummy username - we chose to use email as it allows pairing with other authentication methods (oauth, magiclink, etc.) that are email based
Just use the latest & greatest open-source library, no?
AKA: We do Auth, you do you.