Sensor for Zappi boost remaining amount

[markcocker]

I am on the Intelligent Octopus Go tariff and have the Zappi in Eco+ mode.
When plugging in an EV to the Zappi, Octopus will create a charging slot and during that slot instruct the Zappi to boost for a specific amount of kWh.
Whilst boosting, this integration will set the sensor sensor.myenergi_zappi_nnnnnnnn_status to Boosting.

I would like to also have a sensor or attribute on an existing sensor that gives the amount of kWh remaining before boosting will stop. This will enable me to estimate when it will finish.

I suspect this must be available via the MyEnergi APIs as their phone app displays it.