Centralight 3157100 (Pearl Thermostat) Trigger EM Heat through Zigbee

Has anyone figured out how to turn on EM Heat through Zigbee on this thermostat?

Setting Heat and Cool works fine. The Heat/Cool mode doesn’t work but that’s a known issue. I just don’t see a way to set EM Heat through the normal ZHA Climate controls and am not sure how to look up what valid hvac modes are to set a custom automation.

My end goal is to have the thermostat switch from Heat to EM Heat once the temperature outside drops below 32 F, and using the heat pump becomes inefficient.