Actually -- these are not good for accessibility [1] [2] [3] [4] [5]. These companies have raised millions in funding on the false premise that they make your website accessible. This is of course not the case and these companies are currently part of large lawsuits.

Source: I built of them [6] many years ago.

   [1] https://adrianroselli.com/2020/06/accessibe-will-get-you-sued.html (about this particular one)
   [2] https://silktide.com/blog/accessibility-overlays-dont-work/
   [3] https://level-level.com/blog/accessibility-overlays-common-sense-and-nonsense/
   [4] https://www.accessibility.works/blog/avoid-accessibility-overlay-tools-toolbar-plugins/
   [5] https://www.siteimprove.com/blog/seen-through-the-eyes-of-a-blind-user-why-overlays-are-not-the-answer-to-web-accessibility/
   [6] https://oswaldlabs.com/platform/agastya/