I am moderately disabled. I can walk but after about 10 minutes, I get fairly uncomfortable.
Grocery shopping is one of my most challenging tasks. Hoiking my mobility scooter out of my car's boot caused so much back pain for me that the scooter gets left behind and I just break up the shopping into
a few small trips per week instead of once. The moby gets used for things like trips to museums, parks and other events where ambling about over a long period is required.
Most mobility scooters are far too capable for their own good. They are designed to safely transport a person on uneven footpath terrain between the shopper's house and the shops. Once in the shops though, big rubber tyres, heavy batteries, traction motors, staunch frame and a wide stance are largely unnecessary.
If the mobility scooter were pared down to the bare essentials necessary to move the shopper from car to where the trolleys are stored as well as push a loaded trolley around the shops, much smaller wheels, batteries and traction motors can be used.
A superlight folding mobility scooter which could fit in a duffel bag could be based around the steering components and 100mm urethane wheels used on a Razor type scooter. 200-350W of drive power, geared for a ~5km/h top speed on smooth, level surfaces would be sufficient. Running time would be limited to 2 hours at intermittent shop browsing and dawdling speeds. Should require only about 4-6 AH of batteries. Along with a tubular aluminum frame, This would keep total weight down to under 8kg.
The moby would have an adjustable clamp on its handlebars or steering tube to grip on to the push bar of any shopping trolley.
It must have a wide, comfortable seat with a small backrest which either folds or is detachable.
Because Australian shopping trolleys have 4-wheel steering, this moby will require 3 wheels (2 front, 1 rear) and possibly 4 to have a sufficient traction to create a fulcrum against which to force a fully laden (100kg) trolley go around corners. Aussie shoppers know how difficult 4 wheel steering is!
A version of this scooter for US type shopping carts, which steer only with the front wheels, could employ just two rear wheels (one driven) and be supported in the front by clamping on to the push bar of the shopping cart via a clamp fixed to a handlebar which is articulated via a steering head from the rest of the scooter frame to permit steering. This would sacrifice operation independent of a shopping trolley but would further reduce weight.
This idea is slightly more than half-baked. Im very likely going to build a copy of this one. I have several junked Razor scooters and can buy a cordless electric drill for under $30 which will provide all of the drive and speed control for a working prototype.