Based on FIDO standards, passkeys are a replacement for passwords that provide faster, easier, and more secure sign-ins to websites and apps across a user’s devices. Unlike passwords, passkeys are always strong and phishing-resistant.
a passkey can be created for any FIDO2 compliant website. additionally by relying on well understood and maintained implementations of WebAuthn and FIDO2 you would have greater guarantees of security of your authentication.
you're right that at its guts it does still rely on an asymmetric key pair. but FIDO passkey implementations are certified and have been built for enterprise and consumer grade use cases.
for macos and iOS, implementations will normally be using your keychain and are providing an easy user experience on top of your keychain