My takeaway from the article: Buy the sensor, make sure air quality is in the "good" range (green light) and you will be fine. I think I will order a few.
Convincing reasons exist to think that significantly lower levels than are acutely unhealthy have long term health impacts. On top of that, you don't really need a sensor to know whether or not your air has particulate levels that are acutely unhealthy, you just know it.
If you don't care or only want to know if your air is quite bad, sure, buy one of these. I don't think it's a reasonable level, but you do you.
Outside it measures around 400ppm so the base point is good. Inside it measures 480ppm with good ventilation. When someone farts it goes to 2000ppm for a while. So I think it measures 'alright'.