iFixit: we almost never get the devices in advance
Apple never announces detailed information about power, battery capacity and other things, during their unveiling. These details come out after sales begin and in vast majority of cases all of the information come from iFixit. Team of people regularly takes apart to a single screw not only new iPhone, Macbook or Apple Watch, but Android devices, cars or other appliances. On their website you can find detailed manuals, videos, photographs, how step-by-step change the battery, display or upgrade the SSD. How did iFixit even come to be? What pays their bills, when they have absolutely zero advertisement on their website?