Oof! I feel for your friend! I did a trip to DLR a couple years ago with a knee scooter after I broke my foot. It was so painful to my knee with all the varied terrain/pavement textures I folded after a few hours and ended up using a wheelchair the rest of the trip.
Well likely be bringing a dolly or with us this trip for my mom to use when sh can’t take her
ecv through line (eg POTC). I’ll use it the rest of the time as my balance is not awesome due to neuropathy.