We have communicated with ORCID team. Although they want to support the release of email, they could not give us a plan for doing it. Moreover, OIDC implementation does not release other useful User attributes and is not the official implementation. That's why we believe Keycloak should support ORCID as social Identity Provider.
Although, we could implement it as extension, we believe that the best solution is to be in Keycloak core due to maintanance reason ( OrcidIdentityProvider extend AbstractOAuth2IdentityProvider, mapper, ui etc) and we could not implement test like SocialLoginTest in extension.

Actually I think it'll be worse if this is integrated as the core Keycloak team doesn't know anything about ORCID, so the integration would pretty much be unmaintained from the point it is merged. That is of course unless you monitor issues reported against Keycloak to see if there's an issues with the integration, which I doubt you could do in an efficient way.

Rather than integrate this into the main code-base I'd look at ways we can do better with extensions, to allow fully community maintained additions.

It would be no problem for us to monitor any issues related to the integration of ORCID with Keycloak. This is something that we will in case have to do since ORCID is required for all our Keycloak deployments. You see ORCID is one of the most popular authentication options for research & education scenarios, including access to the European Open Science Cloud (EOSC). But having ORCID as a core social plugin would simplify things since we can then make use of the SocialLoginTest to identify issues if there are breaking changes.

I'm going to close this as mentioned we can't really support or maintain this capability at this point. Please provide an extension for this provider, list it on the website, and open a discussion around how we can provide a better approach when it is maintained as an extension.