Usually when wanting something to start talking over wifi I recommend using a raspberry PI.
You could look at the raspberry PI zero with the Pimoroni Enviro+ board.
A few mods to access some new pins to control the lights and sense the door is easy enough.
If your trying to design something as a marketable product you’d probably want to look at using the esp8266 boards. I havent used them myself before but I’ve heard good things about their wireless and data collection capabilities. -> https://www.adafruit.com/product/2471
Sadly I cant help with board design. I can do some basic programming for functional prototypes but nothing to put to market.
Let me know if I can lend a hand. I’m concerned about needing to drill a whole into the humadoir to mount the external sensor. Or if that’s not a big concern.
I am certainly willing to lend a hand with either. Since you’re making a product, and it’s part of what I do as a professional, it would have to be a paid gig.
What you want is fairly straight forward – feel free to reach out to me here, or in email: