Accessibly overlay vendors (remember: overlays do not work) have produced a handy list of such tools: https://github.com/a11yedge/overlays/issues/1
The GitHub issue is titled “Review what existing overlays actually do“ and from my point of view, it’s somewhere between “nothing” and “harm”, with a sprinkle of normalizing ableism. Cool, cool. Cool.
(Via @aardrian)