Working with attachments with Skuid Platform

Although I have successfully used Google Drive using OAuth 2.0 for clients who have google accounts for their users, I’m looking for a file attachment solution for clients that don’t have google users. So far, I have been unsuccessful in getting a google service account to work with skuid data sources. I’m open to other platforms that might work with a service account instead of individual user accounts.

As near as I can tell from the documentation, support for box, drop box, OneDrive, & SharePoint have been dropped even though they exist in the dropdowns selections when setting up a datasource. Anybody have any suggestions for solutions that work with skuid platform?