Azure AD B2C custom policies currently allow you to use any OpenID Connect (OIDC) identity provider. We've extended this capability to the built-in user flows. Just like you can sign in users into Azure AD B2C via popular social identity providers, you can now use any other OIDC identity providers in your user flows. You can even use this to allow users to sign in to Azure AD B2C using their Azure AD work accounts.
Learn more