You're mixing up Human OIDC and Machine Flow OIDC. You can use OIDC to log in as a user, but you can't use OIDC to allow federated trust from something like Github Actions.
If you can find an example of OIDC with Github Actions and Harbor I'd love to see it.
If you can find an example of OIDC with Github Actions and Harbor I'd love to see it.