Yep! You can delegate to another Identity Provider (IdP) by adding a JSON file to your domain (we're looking into DNS-based ways of doing the same), but afaik, there aren't any publicly available IdPs that accept delegation yet. Ozten is working on one.
Also, we still haven't completely shored up the IdP-facing API (there are a few rough edges to fix before committing to it), so the specifics are still subject to change. https://mockmyid.com/ and https://eyedee.me/ are both open source, example IdPs that we're using for testing.
Also, we still haven't completely shored up the IdP-facing API (there are a few rough edges to fix before committing to it), so the specifics are still subject to change. https://mockmyid.com/ and https://eyedee.me/ are both open source, example IdPs that we're using for testing.