As per Siamak's feedback: https://coreos.slack.com/archives/C01RQH8KQ87/p1620229487167200

Remove this sentence - 'You can use Keycloak or a bundled Dex OIDC provider.' from the SSO docs. We don’t support anything other than RH SSO which that page describes:
https://docs.openshift.com/container-platform/4.7/cicd/gitops/configuring-sso-for-argo-cd-on-openshift.html