The motor can't produce 250 watt on a continuous basis, although it does have a peak output of 350 watts, however the motor size and throttle type have nothing to do with the question, just a red herring.
I am looking for ideas how to transport the bike from home to a place it can be safely used, look at a mobility scooter and there are many designed to be wheeled on/off buses, trains etc. in their compact form. As soon as my bike is folded it can't be wheeled and is rather heavy to carry, not point reinventing the wheel, so asking how others carry their bike to place of use.