> there’s not much you can do with a residential AQI sensor without adding a bunch of other automation controls.

You don't need automation. I have a portable CO2 monitor (aranet4) and it gives me an indication of how effectively the air is being exchanged. I've learned that my desk location at home is ok during summer and winter, but when temperatures are moderate the furnace isn't running as much, and the CO2 will get quite high. I keep a window cracked when I work there and it's enough to bring it down to reasonable levels. I didnt know this information before getting it. Similar when I was visiting relatives over easter - the CO2 in the bedroom got up to 2500ppm wile I slept (old house, sealed tight but no forced air circulation). I opened the window for the rest of my stay.