I think #Anki holds a great deal of potential for #blind learners of #languages and other subjects:
The desktop app uses Qt 6, so isn't entirely unusable. It's also fully open source.
The iOS app is extremely usable with VoiceOver, albeit relatively expensive for a mobile app at £24.99, and not open source.
The web interface is usable, but would currently cause people to think more about how to use it than the actual subject they were studying. Still, with some user scripting, it could be workable.
And finally, all Anki functionality is available via their Python library, which could be used in a command line app or more #accessible frontend.
Of course, the issue is always the time needed to take things from where they are now to where they need to be. And I suspect a significant challenge would be having screen readers speak/braille things in the correct language as hopefully declared by each flashcard.