Air quality sensors are so sensitive, I suspect that simply parking them in the general vicinity of an ongoing roast will produce a useful reading.

This is not a product endorsement or recommendation, but just lightly searching Amazon found this for $36: https://a.co/d/8iMSF2R. Indicative of how mainstream air monitoring has become - and it comes in two colors

It's also not lost on me that the CO2 levels I'm measuring during a roast are way(way) higher than the safety alarm thresholds for these handheld testers...