It will depend on how complicated the layout of the file is. Luckily, once the Canvas page has been created, you can easily make changes to layout, style, and additional accessibility concerns!
The conversion quality and accuracy will depend to on how accessibly the original document was created. Simpler files that already have headers will obviously render as much more compliant pages than a super complicated and inaccessible file that lacks tags and utilizes visual layouts.
The key is that once you’ve converted a complicated PDF, you then have the ability to edit it and make it more compliant than it was!
For example, if that original file had images and tables that were not compliant, you could scan the new Canvas page with UDOIT and quickly add alt text and table headers through the UFIXIT interface - which will be MUCH easier than editing the original document to make these revisions.
Accessibility requirements in Canvas are much simpler to meet than accessibility requirements for files, so it simplifies the workload there as well.
Plus, if your institution also licenses DesignPLUS, your users will be able to see accessibility warnings in the DesignPLUS Sidebar, any time they are creating or editing a Canvas page - helping to ensure your content stays fully compliant.