I’m not familiar with “groups” inside of homey. Is this just a flow you activate inside of homey (And switch all the lights one by one inside the flow)? Or can a group activate a flow (Like “If group gets activated” or something). If so you could just send a custom MQTT message out of a Homey-flow and act accordingly inside of Node red.
You could also just keep track of every light inside of Node red (save state on change inside a global variable) and check on light activity if all other lights are switched on. if so, you know if this group is on.
You could do the same inside Homey with flows.
