3. OAuth 2.0 for specific custom Customer Integrations. A standard product plugin does not currently exist . However custom work with customers where required can be attempted.
4. G-Suite SSO through the product plugin route is available in Zing .
Zing has the capability to create custom authentication integration protocols where the users are in excess of 1000 active users .
You may reach Zing Business or Zing Authorized Business Partner's SPOC/ Teams to understand the commercial investments required to make the custom integrations work for your organization.