As long as it would be feasible to serialize the unverified user
contacts into a JSON within the payload size limits (5MB), it might
work. However, there are other details from this question that are not
mentioned here, that will also determine the feasibility of creating
such a workflow. Specifically, it is not clear whether the push
notification will need to be sent to each user in unverified segment,
whether the push tokens exist in ACS etc. From External API point of
view, the main points to...