Don’t bother with the CCS811 for CO2 measurements - it’s “CO2 equivalent” readings do not correlate with those obtained from CO2 sensors.
BME680 gives a ballpark number for IAQ and I would leave it at that. See page 9 of the following for practical uses: https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BME680-DS001-00.pdf
Enabling BME680’s gas sensor sucks power and you’ll be lucky to get battery life longer than 12 months. Additionally, enabling the gas sensor will warm up the interior of the Ruuvi tag puck and distort temperature and humidity readings
BME680 does not like small particulates - filtering has to be good or else the sensor cavity gets contaminated with particulate junk and readings diverge drastically. (i.e. do not walk around Beijing with your BME680 on bad pollution days)
From my experience, the BME680 (like the CCS811) adds nice bells and whistles that are good for marketing but provide false security because they do not accurately represent the datums that they are measuring.
We’ve evaluated the BME680 and similar sensors and came to the conclusion that MAYBE, just MAYBE, in 2 or 3 years, low-powered gas sensors will be at the maturation stage that they can be used as reliable sensors in mobile/portable applications.
And yes, I’m ready for the backlash of comments regarding my critique. Sitting on my workbench shelf is a row of sensors that have been under test for months. Trying to evaluate the trade-offs between measurement quality, power consumption and cost. Low cost sensors look great on marketing brochures but quality of measurement (QoM) is poor and my database of recorded measurements does not correlate with what marketing brochures promote. I trust what I measure rather than what I am told.
The BME280 is a good sensor at a reasonable price so stick with it!