Is the only way to get a roster with photos for the students themselves to upload a photo?
Some schools automatically upload the student photos for the students using the Canvas REST API. Those schools generally don't want students to upload their own photos. Other schools, probably the vast majority, allow students to upload their own photos.
If your school has student photos in their student information system (SIS), it may possible to obtain a photo roster from the SIS.
Retrieving data ...