The user taught her service dog to help when the wheelchair goes uphill. The user holds the leash in one hand and operates the wheelchair with the other hand, so the dog does not have to pull the user’s entire weight.
A stronger dog could manage the user’s full weight. Instead of holding the leash in her hand the user can use a leash that goes around the waist with a quick release feature.
For leash with belt see spinalistips.se/en/tip-dog-leash-with-belt