[barryrandall]

Nothing else is suitable for multilateral, full-mesh federation yet. The OIDC multilateral federation standard hasn't been finalized or fully implemented yet, and it takes years to coordinate this kind of change in a federation.

[gorkish]

So use SAML for that part; education is still a big market and they have a case for delegating the responsibility of establishing and managing trust relationships to a federation provider that most b2b and b2c applications will not have. Fortunately most of these identity systems are happy to proxy for downstream OIDC/OAuth IdCs anyway, so the argument that you may not want to implement SAML IdC in your own application is still valid even in this context.