Thank you for raising this concern to the Google Ads API Forum.
Unfortunately, there is currently no possible way to get the unique users using Google Ads API, you can only get this information in the Google Ads UI.
However, we already raised a feature request to my team so that it will become possible to retrieve this information using API. Our team will review it if it is feasible to add in the API. For the meantime, please follow our
blog as we will post any relevant updates when become supported.