Hello @suf ,
Thanks for reaching out.
This scenario you could leverage either B2C or Azure AD external identity providers feature by which you can set up federation with any organization whose identity provider (IdP) supports the SAML 2.0 or WS-Fed protocol.
The Azure AD metadata can be downloaded from this URL:
https://nexus.microsoftonline-p.com/federationmetadata/saml20/federationmetadata.xml.
For customers in China using the China-specific instance of Microsoft 365, the following federation endpoint should be used: https://nexus.partner.microsoftonline-p.cn/federationmetadata/saml20/federationmetadata.xml.
Configure SAML/WS-Fed based identity provider federation with AD FS (preview)
Federation with SAML/WS-Fed identity providers for guest users (preview)
To learn more about what are External Identities in Azure Active Directory, refer: https://learn.microsoft.com/en-us/azure/active-directory/external-identities/compare-with-b2c#compare-external-identities-solutions
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