> What is a passkey?
> Any passwordless FIDO credential is a passkey.
I would recommend [1] as an excellent overview of the FIDO2 and WebAuthn standards that underlie passkeys. depending on how you use your Yubikeys, you may already be using these standards.
if you already have a password manager you're happy with, the appeal of adopting passkeys is somewhat marginal. if you're using your Yubikeys for FIDO2-based MFA you're already getting the majority of the benefit.