ishabana:
My choice for this UNO + WiFi one is completely related to 2 main things: it accesses the internet, And the black color is fitting the installation.
So now we know. When I said
Unless you are buying it for reasons other than functionality
I was going to add
like the colour of the PCB
but I managed to restrain myself. It's a shame really, the Node-MCU does twice the job for half the price, but comes in a rather uninspiring shade of dark brown.
A definition of API is
a set of functions and procedures that allow the creation of applications which access the features or data of an operating system, application, or other service.
I don't know if that means much. I guess the number of around 5-8 digits is just an input signal, and why you need three devices to receive them is not clear and I don't suppose that matters, but board 4 is probably redundant.