@Krishna Eyyuni The REST API doesn't necessarily provide any specific benefits for Bulk uploads. The ability to upload many files to the staging area is to help facilitate create a document that is made up of multiple files (which is primarily supported only for Image documents). You would still need to call the POST method on the documents end point for every document you want created.
Executing scripts (Workflow, WorkView, Client, etc...) already tap into the Unity API, and there is no way currently to share that session/license with the REST API.
So based on the information you have provided and the two factors I have mentioned, I don't think there would be a benefit to try and use the REST API for this from within a Unity script. I would simply use the Unity API methods to perform the upload.
If the volume of the bulk upload is truly significant, you could also look at other means to write the files out for a DIP process to pick up rather than doing it through a script.
