Airgradient's popular indoor air quality sensors are the first devices of their kind to be officially certified as "Works with Home Assistant". These open-source devices do not require an internet connection and enable local automation with air purifiers, air conditioners, or humidifiers and dehumidifiers.
I’ve had one of these for a few years now, the CO2 sensor is the primary sensor I was interested in. I ended up putting esphome on mine because I didn’t want any cloud dependency, but glad to see it’s officially supported in home assistant now.