It's also stealing massive market share from JAWS.
https://wiki.debian.org/accessibility https://www.debian.org/devel/debian-accessibility/software
ORCA is probably the strongest FOSS competitor of JAWS:
https://wiki.debian.org/Orca https://help.gnome.org/users/orca/stable/
I don't know whether Debian would be the best choice for OP or not. In my experience, I wouldn't install any new OS for someone unless you are willing and available to help the person until they get the hang of it.
My parents have been using Linux (formerly Debian and now Mint) for over a decade after they got fed up with Windows. I still have to help them from time to time, but I think that would also be the case with Windows, except I would be trying to remove malware instead of showing them how to burn a DVD or what have you.
That's not to say that downloading 3rd party applications for Windows doesn't scare me much more than sudo apt-get install...the OS's just invoke different levels of trust in me. Anyway, XP was the last truly vulnerable version of Windows and thankfully it's been laid to rest.
My brother is blind. He has been using JAWS for over a decade.
I love OSS, and I know many distros have screen readers.
Yet JAWS is just out there ahead.
If she finds it too complicated: try and simplify things. Remove unneeded icons and menus. Customize her shortcuts. Install TeamViewer (if she is remote).
Keep helping her man. The internet, for my brother, is a place where his limitations are minimized.
Yet to have the world open up in front of you, is all worth it. My brother (just as me), speak spanish. He uses JAWS still the same, although the bulk is in english.
Let me know if I can help you in any way.
PS: If anybody can point me in a direction to help OSS screen reader software, please do let me know. Would love to contribute back.