The bag is a Carradice Nelson Longflap, mounted on a Bagman QR Expedition rack. In that pic, it’s about 12 years old and is now 22 years old. Still going strong. The transverse saddle bag is my preferred carry method for everything other than self-supported loaded touring.
The longflap aspect of the bag lets you do some ridiculous stuff.
The Bosch range calculator will let you get an estimate with taking into account pretty much every factor: wind, hills, load, motor type, battery type, etc. But yeah, with every single company out there, the large print giveth; the fine print taketh away.