Hi! I would look at https://www.aliexpress.com. The original post at Github recommends using esp8266 chip (esp-12e), which is quite old and has it’s own problems. This is the chip I used in my case and for me everything worked out well but I read at their Telegram channel that some people had issues with mysterious reboots and so on.
So now I would recommend some ESP32 chip or even devboard (less soldering), for instance: Wemos (Lolin) C3 mini: C3 mini — WEMOS documentation
They can be bought here: https://www.aliexpress.com/item/1005004740051202.html
Also, I would probably buy several modules as there is a chance that some might be bad or you could also use them in other smarthome projects. Here is a bundle of two: https://www.aliexpress.com/item/1005006710420932.html
Edit: Also you would need DC-DC buck converter like MP1584, XL4015, LM2596, mini360 as the AC unit delivers 14V or something which is too high for 3.3 or 5V ESP modules.