The power supply only puts 5V on the appropriate pins, just like a computer would. Since there is no computer, the drive will do nothing. Even if the power supply has USB-power delivery it won’t actually supply a higher voltage until the device asks for it, and this device won’t.
My innocent brain wants to know what will actually happen
Nothing at all.
The power supply only puts 5V on the appropriate pins, just like a computer would. Since there is no computer, the drive will do nothing. Even if the power supply has USB-power delivery it won’t actually supply a higher voltage until the device asks for it, and this device won’t.
I don’t know for sure but I think if all devices are to spec, nothing happens.