Hello Juan Bautista Ruiz Alzola,
Welcome to microsoft Q&A, Thankyou for posting your query here.
MS Entra external ID(preview): MS Entra external ID is service is specifically designed for managing identities of external users. It supports scenarios like B2B and B2C by allowing external users to authenticate using their own identities, like (external identity providers and personal social accounts)
Since MS Entra external ID is designed for external management and indented to integrate with AVD, this would be more appropriate for your scenario , so that large number of external users can be easily managed.
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