RPi-CO2-Sens precision long-term calibrated CO2 sensor - pi3g.com
Amazon.com: Digital SGP40 VOC (Volatile Organic Compounds) Gas Sensor for Easy Integration Into Air Treatment Devices and Air Quality Monitors, I2C Bus Support Raspberry Pi/STM32 : Electronics
Adafruit SCD-40 - True CO2, Temperature and Humidity Sensor [STEMMA QT / Qwiic] : ID 5187 : $44.95 : Adafruit Industries, Unique & fun DIY electronics and kits
Measure CO2 with Senseair S8 and a Raspberry Pi • joshefin