What is ESPurna?
ESPurna ("spark" in Catalan) is a custom firmware for ESP8285/ESP8266 based smart switches, lights and sensors.
It supports a number of SONOFF devices and feaures e.g. MQTT and Home Assistant integration.
You may find more information on github.
Beware that it requires effort and IT skills to configure and integrate ESPurna devices with home automation systems. This is not products for novices.