I've put about 1900 miles (3000km) within the last 8 months, had one flat tire, disc brake pads are making some noise, very little maintenance needed.
I only leave one battery on this e-bike at a time, the range of single battery is about 50-60 mile, that's carrying 50-60 lb. of additional weight besides the rider (180 lb.)
I just lube the chain, put air in tires and keep riding it. I was hoping to wear out the knobby rear tire to replace it with some narrower, less noisy, more street oriented tire, but still in decent shape after nearly 2k mi.
Fat tires are really overkill for urban, pavement riding.
With new school year starting next Monday, more students, more volume of food to carry than I can load onto the cargo e-bike; likely I will have less trips with the cargo e-bike.