I made a CO2 monitor based on the Sensiron SCD-30 sensor last year before a whole slew of API and build system updates were added to the firmware. I finally got around to updating my app to use the new API and get it packaged as a FAP: https://thzinc.com/2023/01/12/updated-flipper-zero-co2-monitor.html
If you use it, I'd love to hear about it!
Well, I finally got around to updating my CO2 Monitor to take advantage of the latest APIs in the Flipper...