@baldwinsh
I understand what you're trying to do -- my workaround would be:
- Page 1: Embed the Thumbnail on the Student facing Canvas page with the smaller image
- Page 2: Create a 2nd Canvas page including the larger image file only. (I would not have this page added to a module but make sure it's published so that when students do click the smaller image, they do not receive an access denied note)
- Next, add a link to the thumbnail image on Page 1 to Page 2 including the larger image. So that the student's don't get lost if they click the image, you could have Page 2 (larger image page) open in a new tab or on Page 2, include a link/button to go back to Page 1 content.
Definitely not as fancy as a light box can be or coding something with CSS but it's an easier workaround utilizing Canvas functions. I just tried the above option in a sandbox and it seems to be a feasible workaround! I hope this helps!