I designed this home automation system to fit inside a regular 8 channel switch board. Each channel in capable of AC dimming at 240V. Along with this each channel can handle 8 Amperes of current.
The board is based on ESP32 and gives the board WiFi connectivity to be able to control each channel via WiFi. I also developed an Alexa skill to control the modules using Alexa. Later on it can also be integrated with google assistant.
WiFi in a metal box? Hope you plan for external antenna or left the front open.