On the battery. Don't buy a battery where the brand and model of cells inside aren't in the description (e.g. LG, Sony, Panasonic, Samsung...).From there I just looked for the cheapest that had a juicy torque number. It’s on its way. I didn’t know it at the time but have since been able to identify it I think as bafang G900 aka h640?
Motor seems nice, based on this video. At least on the video, sounds relatively quiet for a geared motor.