I am a little sad the original pretty interesting FedCM work got reduced to this. There was some neat work underway to allow using identity providers without the site even knowing the provider! https://github.com/w3c-fedid/FedCM/issues/677

But after some work the team scoped down, to focusing on email verification. I think that's what lead to this spec? https://groups.google.com/a/chromium.org/g/blink-dev/c/rwu9w...