The best way to go about this would be to do a student data export and having "Show students with incomplete data and not photographed." selected.
How can I create a Student Data Export?
Note the following article for reference : https://help.gotphoto.com/hc/en-us/articles/208395906-How-do-I-create-a-student-data-export-
That export will show students that haven't been photographed or with incomplete data.
Alternatively, you can also export the names' list within a job and look at the 'original filename' column. If it's blank, no photo (this may be the easier route).