AZUB BIKE is known for building high quality custom recumbent bikes and trikes. Among many customizations they have developed also the “push brakes” which allow disabled people to ride on bikes in case they do not have ability to operate regular brake levers.
Azub also assemble Shimano Alfine 11 with electronic shifting for easy operation and they have a couple of other options and accessories for disabled riders as well. I went to their WEBSITE and searched for what they have to offer and came up empty handed. If it is on their website I don’t know how you locate it.