I feel like this doesn't follow dedicated rules on the Internet as far as accessibility standards outline by the Web Content Accessibility Guidelines (WCAG).
At the very least for quizzes, whether proctored or not, absolutely need to be accessible to all students, regardless of disability or need.
For me personally, with ADHD, the immersive reader is extremely helpful. The canvas app, Mobile, also needs to address these issues.
I understand the technological challenges to bridge this gap. But it's as simple as noticing how when you copy and paste text, from anywhere on canvas, the instructor should tag the image with an appropriate description. While those who cannot view the image will certainly need advanced recognition, or possible AI intervention, those that even might have poor Internet connection might not be able to view the image.
For instance, while I was in-flight and using the airplanes wifi, I wasn't able to complete most coursework via canvas. Whereas most other websites are quicker to load.
Ramble aside, canvas has its limitations but the immersive reader should at least be activated for these reasons... I don't see any valid excuse for this other than hindering cheating.
Let us not prioritize academic honesty while limiting access to education.