Reading Apple Pencil Pressure in the Browser — PointerEvent, getCoalescedEvents(), and the e.pressure Trap

Building a sketch pad in a browser sounds like a one-evening job. Then someone tries it with an Apple Pencil and the pressure data is gone, because the code listens for mousemove. Or with a mouse and the line is half as thick as it should be, because it reads e.pressure blindly and a mouse reports 0