A friend had s similar medical issue and was using handheld controls while they were recovering. I had a chance to satisfy my curiosity and tried it out and it is easy to use. It is very intuitive and just took a few minutes to get used to working with the device. Mostly getting comfortable with the amount of pressure needed to operate it.
If you decide on this route I would recommend practicing in an empty parking lot for 5-10 min and you are pretty much an expert by then.
Amazon link to a similar device -
CANALHOUT Handicap Driving Hand Controls