Use list returned by Arcade expression to populate dropdown

[Will_CulturalFire]

Would like to write an Arcade query, return a list or dictionary, and use the results to populate a drop down form element. Better if it worked offline, although this seems much more complicated.

Example use cases:

- present a picklist of valid funding codes that is the result of query to a different feature service, filtered to match values provided in form (work type, crew, spatial query). Other service is maintained by a manager via a different app. 

- spatial query of permitting geometry/attributes filters list of available fields for new feature