The Grin bafang wheelbarrow motor has super low gearing:
(It is composed of a small bafang geared hub motor, the G310/311 with 11:1 gear reduction, coupled to an additional planetary gear reduction of almost 3:1 and thus providing a total gear reduction of around 30:1)
Regarding the bold, something you might want to keep in the back of your mind here, is if we are talking bicycle, you need to maintain a minimum speed that will allow you to keep your balance.