Thank you for posting this in Microsoft Q&A.
I understand you are concerning whether it is possible to add a workforce tenant as an identity provider for an external tenant, specifically using SAML/WS-Fed protocols.
As stated in the document, SAML/WS-Fed identity providers are currently only supported for workforce tenants and not for external tenants such as the one you are utilizing.
You can refer https://learn.microsoft.com/en-us/entra/external-id/customers/concept-supported-features-customers for all the current features in External tenant.
Keep checking https://learn.microsoft.com/en-us/entra/external-id/customers/whats-new-docs for monthly updates on external tenant.
Hope this helps. Do let us know if you any further queries.
Thanks,
Navya.
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