Was something similar on kickstarter a few years back. It was rightly pointed out that any dirt / filth / grime would come up and eventually coat the system. Worst case, for places with lax dog toilet laws, you readily risked getting the device and yourself hit with excrement.
Anyone who owns a bicycle can use the Asus Oxiis E250G1 Intelligent Bike Booster to transform it into an e-bike in just a few simple steps. Equipped with a cadence sensor, it is designed to respond just as quickly as a conventional e-bike, and can be charged via a USB-C charger.