Small World has a boarding area on the usual ‘unload side’ for guests using mobility devices.
Usually, those guests would be directed to enter that area without waiting in the regular line or be given a Return Time for that area (although the regular and Fastpass lines are both accessible to a point).
Guests using
ECVs can go all the boarding area with their ECV; the ramped boat is wheelchair accessible, but not ECV accessible. Guests using ECVs can choose to use an attraction wheelchair or transfer to a boat.
You can certainly request to ride the ramp (ADA) boat without a wheelchair. It only has 6 seats, so you won’t all fit if your group is bigger than 6 (it holds six seated guests and one wheelchair).
It may not be as helpful to walk on as you think though; the seats are a slight bit higher than the seats in the regular boat, but not a lot higher and there is not a handrail for walking up and down the ramp. I’d strongly consider using an attraction wheelchair.