When I was a Canvas administrator in higher education, we used the UDOIT accessibility checker from the University of Central Florida (UCF). UDOIT scans your entire course all at once and gives you a report of all accessibility issues that need to be addressed. And, it allows you to make those corrections right within the UDOIT interface…rarely ever needing to make the edits on the page(s) that have issues. In our case, we worked with our on-campus IT staff to install UDOIT in our own local servers. However, there is also a cloud-based version available from Cidi Labs. I’ll provide you with some links to each so that you can determine what might be best for you.
Hopefully, these links will be of some help to you. Sing out if you have any other questions about this…thanks!