This video shows the D1 Mini with the relay board beside an M5Stack Atom Lite device. You can see two complete cycles of the transitions described in earlier project logs. Obviously, you can't see the Home Assistant server controlling things, but you can see how responsive things are. The USB cables are just providing power. All communications are over wifi. 

You may have to look kind of carefully to see the LED on the relay board flashing and the LED on the D1 Mini staying on. For test purposes, I made the timer for the pump only 15 seconds.