Thank you.
While I was not specifically referencing zigbee switches, (my question concerns light switches but also my Amplifier and media player which I have written webthings for), the zigbee switches I have all have read-write on/off state, and since they are actually switching the current if they did not they would be almost useless for home automation.
I’m guessing I’m missing some terminology here to distinguish a switch that does not switch the current, a relay like device that has no direct user interface and a switch that also contains the “relay”.
So the answer appears to be the scene control add on or do as I have with my Amp and media player, which is to have then use a private channel to do this, which feels wrong, but works.