The SMB is the customer, they should already have a single place for all their users and for authentication.
SSO doesn't have to be Google, Azure, Okta, PingFederate, you can run a stand-alone instance of Keycloak for instance and have OIDC and SAML available to provide SSO functionality.
SSO doesn't have to be Google, Azure, Okta, PingFederate, you can run a stand-alone instance of Keycloak for instance and have OIDC and SAML available to provide SSO functionality.