Practical question

Just installed Sonoff switches to operate lights in my room.
Problem is that i do not walk always with my phone. And to be honest it’s much easier to flip the switch rather than pull out a phone.

Hence, want to redo my toggle switches to make them send MQTT commands for lights. Can easily be done with ESP8266 but i can not find a power converter that would be small enough to hide in the switch box.

I have AC 110 in the switch box. Need to get 3.3V for ESP8266.