My first idea is to use Infrared Thermal array sensor like MLX90640 with powerful MCU.  But my DHL order is stuck and on hold on the way. Meanwhile waiting the main parts, I like to start the project V.1 with inhand parts.

The system design of V.1 is simple.

• Use ESP32 (may extend the Camera support later)
• MLX90614, single dot contactless IR thermal sensor which widely used by many arduino and DIY project
• Infrared distance sensor (pair of IR LED and Photo Diode) to measure target body distance under test
• 7-Segments LED display with MAX7219 driver (Rather than LCD or OLED, it is cheap, clearly visible under day light and durable)
• R, G and B Led , to alert normal, warning and critical temperature condition
• A buzzer to beep alert sound
• Used as wall mount or with a tripod stand

Working Principals 

When a target under test is closed to measurement range, ( measured with IR reflection sensor) temperature is measured and displays automatically

If temperature is normal, Green LED will light on with a buzzer single beep, if not  Warning Yellow or Red LED will be flashed depends on temperature and buzzer will beep noticeable tone.

Fig 2. Version-1 System Design