The correct option is SAML single sign on paired with Enterprise Managed Users.

This configuration requires users to authenticate with the external identity provider and it centralizes account lifecycle by making the accounts enterprise managed. The enterprise controls creation, suspension, and membership through the identity provider with provisioning handled by SCIM and access to organizations enforced by SAML single sign on. This pairing ensures that sign in and lifecycle are governed outside GitHub and that deprovisioning in the identity provider removes access consistently.

SAML single sign on only is not sufficient because users still own personal GitHub.com accounts and only their access to the organization is gated. The identity provider does not create or suspend the underlying GitHub accounts and users can still sign in to GitHub independently of the enterprise.

SCIM user provisioning is not an authentication method and it does not handle user sign in. On GitHub Enterprise Cloud it is part of the enterprise managed model and works in combination with SAML for Enterprise Managed Users rather than as a standalone answer.

GitHub personal accounts with 2FA rely on GitHub authentication and only add a second factor. They do not integrate with a corporate identity provider for centralized lifecycle or access governance.

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