Smushing Pictures Not In Media Library

I'm using a job board theme that allows candidates to upload their picture on the front end. These pictures appear to be located in various folders in an upload folder and not the media library. I'd like to be able to use WP Smush Pro to smush those pictures. Is there a way to do this?

Thanks in advance for your help! I apologize if this is addressed somewhere else, but I looked and didn't see it.