Help to select proper controller kit

[admin]

This is not what I am looking for. I want ready input-output module with enclosure and screw terminal connection.
I didn't see chip PCF8574 made like that. It is always done not ready to use. No enclosure, no screw connections etc.

In this case I would better select 2pcs of Arduino Mega 2560. The only problem is that it is hard to find enclosure for Arduino Mega 2560 with W5500 ethernet shield installed.
Your KC868-A16 looks great because it is easy to install, because there is enclosure, screw terminal connections, ethernet and wifi on board and there is possibility to develop own logic in Arduino IDE.
But to make it universal for customers you should offer input-output modules. Otherwise it makes no sense.

what software you draw this photo? it's beautiful.