I stumbled across this thread while searching for something related and thought I'd resurrect it to mention my HASwitchPlate project, which utilizes an ESP8266 as a MQTT-to-Nextion gateway to act as a wall-mounted scene controller. The project includes code for the ESP8266, Nextion, and home automation platforms including Home Assistant and OpenHAB. A PCB has been developed to allow running from AC power, and 3D-printable models are provided to mount the project into a single-gang work box common in North America.

The end result is a scene controller you can build yourself with all the necessary components (software, electronics, and physical enclosure) ready to download.