The system will mainly have (as mentioned above)

1. Light Notification Module(LNM) - This will mainly help to communicate the events/triggers around us with help of PDMs( Physical to Digital Module). This module will be placed where it's easily observed by the people around. Notifications can be distinguished via 2 schemes.
a. Light blink Frequency
b. Different color light

Currently I am using blink frequency method as I have just 2 PDMs to distinguish. Ideally a neoPixel would be the best alternative to implement color modes for notifications.

2. Physical to Digital Module(PDM) - Currently I am developing 2 such modules.

a. Button press notification - this will just intimate the user regarding button press. Context to it will be the placement of the module or the special situation that you want to convey, like calling a person to a particular room.

b. Sound threshold notification - There is a sound level detector that is used. So it could be used to convert door bell sound to light notifications for hard of hearing people.

The system can be very easily modified as per use case and extended. Just change the sensor in the PDM and new notification regarding that context can be implemented, for eg - PIR sensor for motion detection, tilt switch, UV index sensor and many more. It will be powered using mobile phone chargers as the ESP's are power hungry, but with good use of sleep modes in PDM's it can also be battery operated. But as LNM will also serve as the AP point (to make it not dependent on home wifi routers) powering it with AC mains will be better than battery.