Question type to get file from external application

What is the general goal of the feature?
An intent based widget where the external app would return a file.

What are some example use cases for this feature?
We are doing some advance surveying/mapping in an external widget, during the surveying some raw gps logs are downloaded to the app, those logs are then zipped together and should be attached to the submission.

What can you contribute to making this feature a reality?
We can provide an implementation in a PR.

Starting in Collect v1.30, it is possible to define a file field that gets populated by calling out to an external application: documentation. The external application must follow the specification for providing this file.

It is also possible to have an app populate multiple fields including a file: documentation.