Is WebAuth/biometrics supported outside of Unified Login flow on iOS/Android?

We’re exploring the possibilities of using biometric login on iOS and Android, while at the same time providing a fully custom login UI using the SDK or REST API.

In short: the first time a user logs in on a device, we require a username + password. For subsequent logins the user should be able to log in by just using biometrics. We cannot use the Unified Login flow because we want to fully customise the login UI.

So the question is: Auth0 supports biometric authentication through WebAuthn, but is this also supported when using the SDKs/REST APIs outside of the Unified Login flow?