Long time cyclist here. Rode up and down mountains for 30 years with no electric assist. Personally, I would avoid an e-bike. When the grid goes out, and you can't charge the battery you'll curse the enormous dead weight. I would also avoid disk brakes. Completely unnecessary unless your descending a mountain in the rain. Go for simple and standardized bottom bracket and headset sizes (if there is such a thing anymore). As a mechanic in college, the same tools could tune and repair a high-end Italian racing bike or a crappy department store bike.

Sealed bottom brackets and headsets are nice, and maintenance free. However, if they fail, they're done. The old stuff, although requiring maintenance could be rebuilt.

Buy extra tires and tubes. Rotate the tires every 500 miles. A good set will last 2500 to 3000 miles. Brake pads last far longer, but extras aren't a bad idea for collapse, that bike might see decades. If you opt for a sealed bottom bracket, I would consider an extra.

Last, bike style. Mountain bikes stink on the road, road bikes stink off pavement. A cross bike strikes a balance. Tire choices are important here.

Cycling is a joy, at least in environments where cars aren't a constant hazard. If you're around cars, a rearview mirror is mandatory. A quality helmet is mandatory, too, and gloves will save your palms in an accident. Motorcyclists have a saying. "There are two kinds of riders. Those that have been down, and those that will go down." Same apples to bicycles, I have the road rash scars to prove it.