iOS SSO provider expectation

Description
This is a request for clarification regarding scope of SSO support in the mobile SDK.

The first-party Zoom app prompts SSO users for a domain or lookup based on email address:

Therefore any Zoom user with any SSO provider can use the first-party app.

But the mobile SDK demonstrates only the entry of an SSO token.

Is it correct that:

  1. only the first-party Zoom app has access to the SSO provider lookup sequence?
  2. SDK users are expected to implement SSO only for their institution? (i.e. not provide general support for any SSO provider).

Which version?
v4.6.21666.0428

To Reproduce(If applicable)
iOS SDK SSO sign-in prompts for SSO token. Expected was the same sequence found in the first-party Zoom app.

Screenshots
N/A

Smartphone (please complete the following information):
iPhone 11 iOS 13.4.1

Additional context
N/A