M5 Echo wake on button press

Just got the M5 echo speaker to play with and followed this guide

to get it going. Works perfectly with “OK Nabu” wake word and performs the appropiate actions, very impressive.

What I would like to do is use the button on the device to activate “listening”. This would be very useful as basically you have to have the device within arms length for it to pick up your voice anyway.

Seems like a simple workflow, but can find any information on triggering the voice assistant from an automation / trigger.

Can anyone help ?