That status page now also takes app with OpenID integration into account.
On the subject of OIDC, there are several that could be flagged as supporting SSO with little or no extra effort:
So, the flag in the status page indicates not if the app could be integrated, but if the Cloudron package takes care of the integration automatically.
Hopefully since we have OpenID support now, as you mention, we can add more to that list soon 🙂