Pingel, & ,Kliktronic both make electric shifting kits for many models.
To jwebs inquiry:
Linked braking is an ongoing topic. There is no current go to company that I'm aware of, who market's a linked braking system kit to simply bolt on & go onto a machine that is not originally engineered from the factory with linked braking.
When I got back into riding again after my injury a few years back I found this out, & discovered that liability issues preclude any established business from venturing into this market.
I was also informed that the market is too small to entice anyone big from developing a product in that arena.
Many of us have "adapted" whats available to work, with varying degrees of success.
Safety is a big concern & as such it needs to be a #1 consideration in getting back on the road after a life changing event.
Everyone has differing degrees of physical ability after an injury & that factor also makes it too difficult for a 1 size fits all adaptive riding experience.
Best of luck jweb. Don't get discouraged, there are ways of doing about anything if one's determination is strong