Hi Richard,
No, currently pulldata() does not work directly with other data sources such as feature services, sql tables or other dynamic databases or web sources. It only supports csv files located in the media folder. Alternatively you could use a javascript function and the pulldata(@javascript) to query and return results from an external source and then use that value in your calculation. There are some limitations which you should understand with pulldata(@javascript). This is currently only a beta feature and you can find the documentation on EAC here.
An enhancement ENH-000119959 has already been raised for this request similar to yours, although it is currently in our backlog and not a high priority for development in the near term. I would suggest contacting Esri support and attaching your request for this functionality to the existing enhancement request.
Phil.
