Just taking a shot in the dark, but I'm assuming if people were making the needed third party apps for Reddit before, they can repeat this task for Lemmy.
Thing about Lemmy is, since its federated, and fully opensource, even if it doesn't right now, adding an accessible interface is trivial. Be it through forks/pull requests, separate clients or frontends, or as a full-fledged federated peer focused on accessibility
Exactly somebody, anybody, can just submit a pull request for their improvement and it's done. No running the change up the flagpole, getting it approved by the board, or developing a six week communication strategy over a high contrast button.
You are absolutely correct. Lemmy's federated nature basically guarantees that free / affordable API access will always be available to app developers.
I've tried out a couple of the apps, and I know of a few others. I've used Connect (which I'm on right now and enjoying it) and Jerboa which was nice. There's also Thunder, boost is being made, Wefwef, and some more. I cannot speak to any of their accessibility functions, but seeing how quickly they're being made to fill in for what 3rd party apps were for reddit, I would expect the devs would add those same or similar features. Especially since some of the devs who made the reddit 3rd party apps are making them for Lemmy now as well. Again, I cannot speak any of that as fact since I don't have sources, but that's what I would expect.
I would assume that Lemmy is not very accessible yet, but Lemmy’s mobile apps are under a month old. They are making fast progress and I would expect that to change very soon.
However, Reddit’s app has been out for years and they have been told about its accessibility problems for just as long. The impression I get is that they didn’t prioritize accessibility since third-party apps handled that for them. When they cut off access to these apps, they made it very clear that they have no alternatives in mind; they consider the visually-impaired userbase to be insignificant and simply don’t care about their issues.
At least one (Jerboa) is considerably older than that, but just hasn't had a lot of polish put into it because it's a first-party app and the devs were prioritizing working on the server software itself.
Lemmy is open source and built by the community - the apps are all third party - with the exception of Jerboa, which is maintained by the same maintainers as Lemmy and lemmys default web interface.
So if the community want accessibility, they can do it themselves, submitting code to the maintainers for consideration or building their own interface based on the official and universal API that all interfaces use.
Essentially the official app is official only because of who maintains it - it has just as much privilege and the same access as the other apps and interfaces, and that's why the app is not called "The Lemmy App" but rather "Jerboa for Lemmy"
Thee official web interface is official and named "Lemmy-UI" not only because of the maintainers but also because it's bundled with the standard instance backend code - you set up a standard Lemmy instance package, it comes with "Lemmy-UI" as it's basic interface, alongside thus it also includes additional tools and access for instance admins to use to administer the instance while it's running. (Defederation and Federation settings, wether to enabled downvoted, 2FA and many other settings)