Strayfish - thanks for the link, it looks interesting - but initial thought is that this is a standalone custom solution. That is not necessarily a problem, but having a tablet like device mounted on the wheelchair from which the user can control stuff is what I am hoping the Alexa AI and device interfaces will make superfluous.
Instead of having custom hardware and personalised software, it will be much nicer to have a standard bit of kit with a suitable Wi-Fi bridge or hub and the necessary skill in Alexa to allow voice control.
My issue with most aids for the disabled is that they are either immensely low volume and therefore custom and expensive (which also has the disadvantage that the amount of research and development is also not that extensive) or they are built in response to the needs of major healthcare providers in which case they are even more expensive and often no less crudely built.
I'd like to see this whole industry replaced with simple, mass produced home automation tools, AI's like Alexa and autonomous driving solutions - but until then, I will keep chipping away trying to hack existing components to better meet the need in my own household.