WPT details: Web Platform tests for WebAuthn are a mess. We are working[1] on improving the situation. [1] https://github.com/w3c/webauthn/pull/1256
Adds support for web authentication calls from cross-origin iframes if enabled by a feature policy. This brings Chrome in line with the Web Authentication level two specification (https://w3c.github.io/webauthn/#sctn-iframe-guidance).
There are two use cases that the working group is aware of: Firstly, there is interest in banks using this to comply with PSD2 regulations in the EU where they have to authenticate their users inside the context of a 3rd-party service-provider's site. Secondly, some sites wish to outsource their authentication to 3rd-party providers.