As a Kivy dev, I've thought about it before on the desktop (it's come up before and a gsoc student did some preliminary investigation for the best way to do it), but I'll admit I didn't realise the implications on Android where actually this support might be harder due to the mismatch with the normal java widget mechanisms. I do think it's important and will try to take a look at it, but it's certainly true for now that Kivy does not have much support for standard accessibility tools, probably particularly on android and ios.