For multiple services, we've been seeing more and more services adopt JWT-based models for SSO. We have a Hasura integration where we'll generate the JWT necessary for authenticating queries: https://docs.clerk.dev/integrations/hasura

In general, we're pushing for more use of short-lived JWTs to sync identities between trusted parties instead of OAuth. We think this is preferable because it can keep sessions synced, while OAuth tends to result in independent sessions.

Admittedly, we do not run an OpenID Connect server on behalf of our customers yet. This is on our roadmap and will be added soon, and there are definitely some services that we can't offer first-class integrations with until that happens.

Your other point about "every language has an OAuth framework" is well-taken. Our initial launch used something proprietary and this was an issue, but we recently switched to spec-compliant JWTs to benefit more from existing libraries. Here's an example of our current, standard token:

https://jwt.io/#token=eyJhbGciOiJSUzI1NiIsImtpZCI6Imluc18xcn...