This is cool! How does it compare to e.g. an Aranet4? I got one to detect when there is a high risk of COVID-19 aerosols lingering and generally carry it in my bag. That way I can check the reading using my phone.
The accuracy of the Aranet4 is likely a bit better, at least based on the specifications I found (Aranet4: https://www.galaxus.ch/Files/6/6/1/0/2/6/6/2/Aranet4_datashe... , SCD40: https://m5stack.oss-cn-shenzhen.aliyuncs.com/resource/docs/d... ).
With my setup, I can also check the readings using my phone — currently only when I’m at home, since I host the stats website locally — but that’s enough for my needs.