if price is no object get the AirGradient PM2.5+CO2

but Ikea now makes the most affordable PM2.5+CO2 sensor, at $35 a no-brainer

https://www.ikea.com/us/en/p/alpstuga-air-quality-sensor-sma...

in there is a very nice/expensive Sensirion SN63C sensor that costs nearly as much as the Ikea itself

https://sensirion.com/company/news/press-releases-and-news/a...

unfortunately Ikea requires Matter network not plain wifi for communication so I've been looking for a cheap Matter hub or DIY SPR