Enable file references in the google repository, test that you can set the default file type, and disable either type from the admin settings for the repository and this should affect the choices available in the picker. You will need to connect the system account to the google oauth service in order to use links. Use the file picker to add a file to moodle as a "link". Verify in google that the moodle system use has been given write access to the file. Login to the system users google drive. Verify there is a folder structure there mirroring the moodle context tree and at the end of the tree is the file that was linked. Verify that the sharing permissions on the file are that all users can read with the link and the link is not discoverable. Test that following the link opens the file in google. Test that adding a file as a copy exports the file to the correct format and copies it to moodle.