According to the information I was able to gather, it seemed that the answer to that question depends on whether you ask Qt, or a visually impaired user of Qt applications.
I decided the latter opinion was the one I cared more about.
I'm admittedly trying to play it very safe. I have zero proficiency with screen readers, so I'm not really able to independently verify any of this. All I know is that the GUI toolkit is one of the most expensive things to have to change later, so I want to be as close as I can possibly be to 100% sure that I won't end up in a situation where my projects have accessibility issues that I can't fix without changing the GUI toolkit.
Thank you very much for taking the time to research toolkit accessibility and being willing to make it a deciding factor. Which toolkit did you go with?
From what I've read, JavaFX apparently has its own accessibility problems; for instance, I vaguely remember reading that if you used Alt+Tab to switch to or from a JavaFX window, JavaFX would automatically activate the menu bar. I've never used a real JavaFX-based app though.
As much as some of us might dislike it, I think the safest choice is Electron, or just making it a web app if that's an option.
I chose Electron, largely because there seemed to be a lot more good documentation on how to maintain a decent level of accessibility.
Electron does have its downsides. On the upside, one nice thing about making screen reader support non-negotiable is that it took so many options off the table. So I was at no risk of analysis paralysis, and I don't have to worry about second-guessing my decision.
Neither have I; from what I can tell, the only place that JavaFX seems to have a foothold still is "intro to software engineering" classes in colleges.
The basics work, however for example screen readers do not anounce context menus under Windows, treeviews are not providing all the information they could see (https://bugreports.qt.io/browse/QTBUG-81874?jql=text%20~%20%...), etc. But in the end, if you need somewhat more advanced widgets (tables etc.) and you do not want to implement the gui on each platform or use Electron or similar, you have no choice.
