IdP-Initiated SSO

Does nextcloud support IdP-Initiated SSO? I installed the SSO & SAML authentication app, and my SSO guru and I looked it over, but it only seems to support the default login lifecycle. We have nextcloud setup behind a proxy, and it handles the IdP automatically, so the normal way is to send a POST with the SAMLResponse as a query parameter, but we need an endpoint.

Thanks!

closing in favor of How to do IdP-Initiated SSO?