thanks for the suggestion. Indeed, we are currently exploring the use of Discourse OAuth2 Basic with EGI Check-in.
I wanted to bring this case to the attention of the community as the possibility to support multiple OIDC providers will likely benefit more organisations in the future and make things easier.
The SAML option was not in the radar, it might be a third option to consider. I’ve found the plugin: GitHub - discourse/discourse-saml: Support for SAML in Discourse · GitHub