Thanks for those links- this is something I'm interested in as well. I'm working on a RasPi Zero hat that has a CCS811 for eCO2 and VOC, a BME280 for humidity, temp, and barometric pressure, and a header for a SDS011.
I'm interested in indoor air quality, so just looking at PM2.5 trends over time would probably be enough for me. An error of 2x without calibration makes it useless for any sort of air quality index calculation, though. Maybe I'll include a header for the HPMA as well and compare the two.