yup, my thoughts exactly, don’t really see a any benefit for using USB-C here. What would be good of course is to have any standard at all for these connectors.

That’s what I thought too, initially. But then I thought that maybe there is a good reason for the specific 54.6V figure. But I didn’t dig deeper

Don’t really have a clue about e-bikes. But looking through some e-bike chargers on Amazon, they have maybe 100 W to 200 W. USB-PD (EPR) apparently supports up to 240 W. Do note that the e-bike chargers are rated at 54.6 V, though, while PD only supports up to 48 V, and I guess the higher voltage might be required for the cell chemistry. So idk if it would be possible to design your batteries around the USB spec. In any case, you would need a separate charger and special cable to support 5 A over USB anyways.