Question(Advice wanted): External "display and control unit" with pi zero

Hardware
3
  1. See 2. and 3.
  2. I want to display e.g the state of above-mentioned arduino-based light sensor or the temperature (via two hue motion sensors) or some status info (CPU Temp, throttling and undervoltage state, etc) to see if my "main pi" is properly running
  3. I want to use the buttons to e.g control my lights or (via some nodes) my echo devices. I want the button being pressed to trigger an event in NR that i can use further
  4. On the Esplora, i'm running some code for detecting how bright it is in the room and send this to my "main pi" to control the light based on this value. I could attach a display to it, but it should be in another place than the esplora because of the sensor. I'll think of this as a kind-of temporary solution until i find some better solution for this.
    Btw: The Pi's GPIOs are used for a unicorn hat 8x8 LED Matrix and can't be used because of that
    Do the D1 mini's have an integrated Wi-Fi module or do i have to get an external one?
    Thanks
    Aaron