Kathy - OEM Sonoff FW works in closed environment. For test purposes I flashed one device with custom FW and it is possible to control it via web now, need to know IP only. It offers possibility to use MQTT and Domoticz as well. I am trying to explore this possibilities now. Due to their broad portfolio (various devices like temperature/humidity switch, power metering switch, dual channel, 4 channel, light, touch switch etc.) I thing that more than one adapter will be needed.
Anyhow, to have a possibility to control it through Mozilla IoT wold be great.