These small geared motors are actually very good assists and will make 20% hills easy with pedal assist, if you have any kind of slope stay away from direct drive low wattage hubs as they suck big time.
The nano-motor use roller type gear and the contruction does not seem robust.
P2 motors are better choice.
I have read accounts of these motors losing drive altogether. There was a guy doing a ride on one to Brussels from Wales to make a point about saving the planet or some such crap (see link below). He averaged a speed of 10 mph with much pedaling from him and covered about 50 miles a day. His motor broke down within 500 miles leaving him without drive. Since I have pedaled my 16 inch folder well over 2200 miles at a 12 mph average speed without any misadventures, this does not seem like progress, especially since the kit cost about £500! The other day I pedalled my Taiwanese Brompton clone at an average of 17.4 mph for sixteen miles up and down a dual carriageway. I am an old git of 56 years old so the nano motor can't be up to much.