HTML-based web pages (created on WordPress or Brightspace) are the most accessible for screen readers.
PDFs became a standard due to differences in operating systems. PDFs are not inherently accessible unless the original
Word is better than PDF?
Powerpoints in their own class. Publisher supplied are often not accessible.
Powerpoints to PDFS would require every slide to have a complete alt text as each slide comes as a single image.
You can take the material from your slide deck and put it onto brightspace or WordPress pages.
What is the pedagogical value of the powerpoint in your asynchronous course? What are the pitfalls/time needed to make accessible.
Microsoft all has built in accessibility checkers, but doesn’t get everything or tell you how to fix things.
Mac: Tools – Accessibility Check
Windows – Review