ishabana:
First, and since I am looking for a minimal setup, what do you think of this board:
RobotDyn UNO+WiFi R3 ATmega328P + ESP8266 with 8Mb flash – Art of Circuits
I can't view that website but I can guess what it is from the URL. The ESP8266 WiFi chip used on that board is a good option for your project. There are two ways of using this chip with Arduino. The first is to use it as a WiFi interface connected to a primary microcontroller, which is what you'll be programming. The second is to use the ESP8266 standalone where you are directly programming the ESP8266.
That board is of the first usage. The benefits of that system are:
- The ATmega328P microcontroller is the most popular in the Arduino world over many years so you will find a ton of information on it.
- The ATmega328P microcontroller has more IO pins, which allows you to easily connect more sensors/switches/accessories to the board.
- The ATmega328P can run at 5 V, which is the common interface voltage for Arduino accessories.
The benefits of using an ESP8266 standalone are:
- It's a much more powerful microcontroller with way more memory.
- It's cheaper (since you don't need to pay for the extra microcontroller).
- It allows more advanced control of the WiFi functionality.
So they each have some advantages. Over time, the Arduino community has been moving more and more towards using the ESP8266 standalone. Since it doesn't sound like you actually want to connect any physical components to the board and you expressly asked for a minimal setup, I'm leaning towards the standalone option. A nice ESP8266 board is the WeMos D1 Mini, which is available for a very reasonable price. There are a couple other WeMos boards that are also good options.