The "average" ebike will handle a 10% uphill grade for a mile or so but can overheat the motor if you go much farther. This varies greatly though from bike to bike.
I'm riding a 1200 W geared hub motor, the kind that the California vendors won't sell because people burn them up riding up to the park at the top of the Sierra.
I cross 77 hills in 30 miles on my way to my summer camp, 3 of them 15% grades of 100' or so. I have 4000 miles on the motor I paid $221 for from ebikeling. The only problems have been the cover screws have to be retightened twice, even with blue loktite on the threads. This does not require removing the wheel or brake disk, just a screwdriver. It makes thumping noise when it requires maintenance.
DD hubmotors (direct drive) are even less prone to overheating, if your grades are not as steep as mine. Those are better at higher speeds than grinding up steep hills at 6 mph as I do on my route.
There are mid drives, but the power flows through the chain, which limits chain life to 4000 miles at most and in the 11 speed (skinny) variety, as low as 500 miles. Also most mid drives drag badly with the power off, which is how I ride most of the time for my health. Exceptions are Shimano and Yamaha. I use the motor for commutes with wind >12 mph in my face, which can cut my self power speed to 5 mph. Also portions of trips over 25 miles.
If you ever intend to buy groceries on the way home, my yubabike for cargo shown left can handle 80 lb cargo with my 170 lb weight. My pants inseam is 28". That is the drop frame for small people. Magnum has some inexpensive step through models with fenders, and dealers in various cities. 2" tires are adequate for comfort up to 15 mph, and I hit 30 downhill sometimes if the pavement is good. The bodaboda will not accept a suspension seat post or replacement suspension fork as the post diameters are non-standard. With the pannier bags and an extended deck of aluminum angle, I can live without a car. I occasionally rent a U-haul truck for building supplies or piano moves.
BTW I measured the slope of my steepest grade with a 8" level from K-mart with a 6" straight part, and a ruler. 7/8" rise in 6" is 14.6%.