When the quartz halogen bulb came out, it was recommended not to dim them as it reduced the life, and with the CFL it was nearly impossible to dim, so by time the LED came out all my dimming switches had gone. And the LED when dimmed with a external dimmer the colour stays the same, so in the main better to dim with a smart bulb rather than an external dimmer.
The cheap dimming units seem to use a single feed to many lamps, and there is a problem with UK homes where we can have multi circuits in one switch plate, and they also tend to link using sensing wires or wifi not the same way as the old two way switches, so often you can't use a mechanical switch as the second unit.
This
seems to show a relay which can dim and use the existing on/off two way switching, but they are mechanical switches not touch panels, there is a non zigbee version, but since it requires a neutral it would need mounting in the lamp not the switch back box, I have a non dimmer version doing my landing lights, but with mine the switches are extra low voltage. The non zigbee version
seems to be wired the same, up to now I have not lost the zigbee connection to mine, if I ever do it is a big job, I will need to dismantle the lamp to push the buttons to reset, in hind sight should have fitted the unit in a box in the loft so easier to access.
Lightwave seems the most likely make which will allow two way and touch control,
but it does not allow you to use the old mechanical switches.
