When researching ways to go about modifying an IKEA Vindriktning I found these links quite helpful:

• Sören Beye's original mod on GitHub
• @lond's #IKEA Vindriktning PCB 
• Michi Lehr's build including a CCS811 sensor
• Blakadder's build with all the sensors, especially the tip to use the tasmota-allsensors build in order to not have to build a custom Tasmota version
• Usage of WS2812s with Tasmota
• List of Tasmota compatible sensors

Just now I came across @Catalin Sanda's #IKEA Vindriktning Daughterboard... if only I had found this sooner...

On the software side I used

• Tasmotizer to flash tasmota-allsensors (see above)
• and followed Jon Oxer's instructions on setting up MQTT, NodeRed, InfluxDB and Grafana

I read somewhere that Apparently the Vindriktnings color thresholds are a bit optimistic so I tried to find more reliable ones for PM2.5, VOC and CO2 but I'm not very happy with the results:

• PM2.5: https://blissair.com/what-is-pm-2-5.htm 
• PM2.5: https://en.wikipedia.org/wiki/Air_quality_index#CAQI
• VOC, CO2: https://cdn.hornbach.de/data/shop/D04/001/780/491/871/060/10176848_Doc_03_DE_20201103134757.pdf
• CO2: https://www.breeze-technologies.de/blog/calculating-an-actionable-indoor-air-quality-index/

If you have a good source, please leave a comment.

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Edit 2022-06-22: Added link about Vindriktning color thresholds.

Edit 2022-08-29: Just came across this thread on home-assistant.io with a list of even more builds.