I have Apollo Automation MSR-1 (it does multiple things, including CO2 and mmWave movement/presence detection; they also have AIR-1 which tracks all sorts of ai

I have Apollo Automation MSR-1 (it does multiple things, including CO2 and mmWave movement/presence detection; they also have AIR-1 which tracks all sorts of air quality metrics such as VOC etc), flashed with ESPHome reporting to my Home Assistant setup. It's main advantage is that it's extremely affordable compared to the competition, and entirely local. Also I have a Netatmo Indoor Air Quality Monitor (requires their cloud service to work, but there's a Home Assistant integration too) which, alongside PM2.5 and CO2, also does sound and alerts me when music/etc. is too loud.