B2C lacks native support for work accounts from Microsoft Entra (AAD). One option for you would be to add Microsoft Entra ID/Azure AD as an identity provider by creating a tenant and configuring it as an identity provider in your B2C tenant. You can use Custom Policies to enable sign-in for users from a specific tenant (Azure AD). You can refer to this guide to set this up.
You can add local accounts in B2C as an IDP, which will allow users in your tenant to sign into apps.
Let me know if this helps and if you have further questions.
Here are some additional resources:
You can also leave feedback to enhance the out-of-the-box functionality so that the product team can respond directly here: https://feedback.azure.com/
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