I have a Google Cloud application that operates with the drive.file OAuth scope among some other non-sensitive scopes. I want to enable our app users to select their existing files for use within the application. However, our design and product teams have rejected the use of the Google Picker for file selection from Google Drive, as it disrupts the user experience flow of our service. My question is: what alternative methods can we provide to our app users for selecting their existing or shared files, while still adhering to the requirement of using the drive.file scope?

This is the scopes I am using so far:

  ".file",
  ".install",
  ".profile", 
  ".email",

The application uses user OAuth credentials to access the user Google Drive files. Is using a service account a better approach? In that case how to make the service account access the user's existing files?