Accessibility is an interesting space for quality because under the ADA you can be sued for it and be exposed to huge liability.
Accessibility testing sounds like something an LLM might be good at. Provide it with tools to access your website only through a screen reader (simulated, text not audio), ask it to complete tasks, measure success rate. That should be way easier for an LLM than image-based driving a web browser.
But accessiblity on the frontend is to a large extend patterns - if it looks like a checkbox it should have the appropriate ARIA tag, and patterns are easy for an LLM.