I hope you didn't take Po Lu's response as a rejection of your
proposed patch. Given that you can incorporate his review comments
regarding the place to call x_maybe_send_physical_key_event, I see no
reason for us not to accept such a feature, once cleaned up and
properly documented.
Also, please recall that I preferred these events to be blocked
(a.k.a. "discarded") subject to a special variable, instead of being
inserted into the input queue and then ignored due to some keymap.
IOW, I'd prefer this to behave like track-mouse.
Thanks.