WebUSB is indeed great, but this particular tool would not work in it, as it does something different (HID input remapping as opposed to, or maybe in addition to, reprogramming a HID device to behave differently via vendor-specific commands).
Some things could probably be pushed to the HID layer, but that would require a at least firmware redesign of the mouse, and some kinds of complex shortcuts are probably better done on the computer OS than that of the HID device, which is inevitably working with much less context.
Some things could probably be pushed to the HID layer, but that would require a at least firmware redesign of the mouse, and some kinds of complex shortcuts are probably better done on the computer OS than that of the HID device, which is inevitably working with much less context.