I just became aware of the fact that version 6.1 of Juce, which is a UI library often used to develop audio plugins, is now officially released as stable. THis version is particularly important because it includes screen reader support. https://juce.com/discover/stories/juce-6-1-released
What this means for you is that if you find a plugin that's not accessible, but uses juce which is extremely likely, you can now reach out to the developers and ask if they'd be willing to upgrade the version they're using. Now that it's not a development feature it's more likely they'll do it.
If you see an inaccessible plug-in and want to check if it uses Juce, press NVDA+f1 when the plug-in is focused and look if the window class says juce. Jaws probably also has a way to get this. On a Mac, you can run strings on the plug-in binary and Pipe its output to grep and look for juce that way.