For folx considering air quality monitors following the LA fires. A few months ago I purchased an Air Gradient One for indoors due to fires near my hometown. You can use the code "SABP13ET" for 10% off (SmartHomeJunkie). It's open source, homekit compatible, and hackable, but also works well out of the box. You can view historical data from web view on your phone or laptop. Having a monitor allowed me to determine if an air filter was necessary from the fires and on the day to day reminds me to air out the room from CO2 build up or from running my stove, even when out of the house. The discounted DIY model was as easy to build as three pieces of legos and a few screws. https://www.airgradient.com/indoor/
Other monitors I considered from reviews on reddit where the HotKrem 5-in-1 and TemTop M2000c on the more affordable end. I also considered mainstream competitors like Air Things, Purple Air, and Govee. I decided that the price was not worth the performance, though there are plenty of people who are satisfied with their purchase.
https://www.airgradient.com/blog/airgradient-vs-purple-air/#:~:text=Comparison%20Table%20by%20Model
You can find several more reviews of different air quality monitors to see if there are models that best suit your needs here: https://breathesafeair.com/amazon-smart-air-quality-monitor-review/