Jump starting phones totally works. I think there is some timing foolery where the phone needs to enable the charger after the boot sequence? Idk but these kinds of shenanigans are life savers now and then.
I tried 3d printing an #ebike battery mount and I'm not thrilled with it so far. It's literally just a bucket, but I got to go for a test ride so that's cool. Crappy pic quality because #pinephone haha