The Federated Credential Management API (or FedCM API) provides a standard mechanism for identity providers (IdPs) to make identity federation services available on the web in a privacy-preserving way, without the need for third-party cookies and redirects. This includes a JavaScript API that enables the use of federated authentication for activities such as signing in or signing up on a website.
To make it work in a way that preserves privacy as a value held by many current users of federated social services, yes.
But it seems like it can be implemented as is in any federated service and improve security for 3rd party frontend apps.
Maybe I’m missing something essential, but holding out for a perfect implementation which may not be broadly adapted might be a mistake on a developer’s part if they want to provide value to ther service they’re developing for.
Oh, I’m not calling for anyone to hold out (well, maybe except until this is widely supported across browsers), just encouraging folks to participate in the experimentation going on in that thread.