7 speeds are adequate if the front chainring is small enough. Smaller front chainrings are easier on the motor and chain as well with less torque being applied.

Few of the e-bikes are designed for serious use as they lack strong rear racks for panniers or even a way to attach an after market bike rack by providing bosses in the frame. I bought the Yamee bikes in large part due to their having very strong rear racks that could support a 50 lbs. load. This is why I would favor a bike like the Blix Vika+ over the Fiido bikes.