Alert Welcome Sensor System

This is a sensor system that could be used to detect whether a person is approaching.
This is a demo video that shows the feature of this.
https://drive.google.com/file/d/18dXX_CxkkV_r9b6Lb3qpZcPS9rGw1GqA/view?usp=sharing
There are 4 main function:
1: The buzzer remain silent when no one is coming, and the light shows green
2: when someone is close enough; in other word, is approaching, the light will turn red
3: when someone is approaching, the light will blink in blue, the the buzzer would sing twinkle twinkle little star
4: when the switch is press, the song would switch between song of joy and little star

There are some scenerio I think this product could be applied to
1: the restaurant would be iused this to detect whether customer are coming
2: people with impaired vision could use this to know whether people is approaching
3: people with hearing disability could also use the light to know whether people is approaching

The circuit design for this is quite simp