Just curious if you've ever reviewed Google's own accessibility documentation for Google Docs. See:
There are also a lot of resources, particularly from universities, returned on a web search for "accessibility Google docs." Here's one from Penn State that talks about the need for the end user of a screen reader to turn on the screen reader features of Google Docs:
Brian - Windows 10 Home, 64-Bit, Version 1809, Build 17763
Explanations exist; they have existed for all time; there is always a well-known solution to every human problem — neat, plausible, and wrong.
~ H.L. Mencken, AKA The Sage of Baltimore