It started out as something to use with ESPHome (though custom firmware will of course work too).
The primary purpose is to control lights, and read from I/O sensors such as DS18B20.
It's got plenty of general purpose I/O pins exposed to connect extra sensors or peripherals.
This particular variant (and the first) assumes a 24pin ATX power supply as input as I have a few of the lying around and they're comparatively excellent compared to your standard 12 volt power supplies. (Additionally the +5V S/B is very useful)

Goal was to use almost entirely through hole components for easy self assembly.
It's also got a plug connector specifically routed for addressable LED steps (+5V, Data, GND).