I have no store bought ebike, and I basically do no chain maintenance at all. The only thing I do is when my chain gets too messy, dirty, rusty then I take a paper towel and chain oil to it, like I did yesterday as I was doing repairs to my ebike with front dd hub from ebay.
My rear wheel had a flat, so it was time to clean up the ebike from the winter crud, look for cracks, check the torque arms and hose clamps, check to see if the drop out slots were undamaged from axle movement all was well. I am set up as a 3x7, but the rd is just a chain tensioner now running one gear, 34 crank and 18 rear freewheel. Its doable for 90% of my daily, everyday of the year, ebiking. Sometimes when I cruise I will come up against a hill where I have to get off the bike. Its a wimpy motor setup. But its ready for a mid drive bbshd in which case I'd be paying way more attention to chain and driveline. Then again I'd just be using $8 KMC Z7 chain probably on a 1x7 having 2 gears on the crank, one fixed for pedal the other the drive sprocket.
I will be trying the Anti-Rust chain that I see on Chain Reaction Cycle and see how that goes.