Mega2560 + WiFi R3 ATmega2560+ESP8266 32Mb memory USB-TTL CH340G Compatible for Arduino Mega NodeMCU WeMos Development board
Amazon.com: KNACRO NodeMCU V3 Lua WiFi Module Integration of ESP8266 Memory 32Mb Flash, USB-Serial CH340G Compatible with ESP8266 32M Internet of Things Module : Electronics
How to upgrade your ESP8266 memory to 4MB (in under 2 minutes) - YouTube