https://forums.developer.apple.com/forums/thread/744835Tip: The Accessibility Keyboard is used for the macOS Keyboard Viewer, which lets you type in different languages when you change input sources. See Use the Keyboard Viewer.
This would be extremely useful for disabled end-users.
My primary interest in this respect is with MacOS, but it would also be a good thing to know if this is possible re Windows and Linux.