Ask HN: What indoor CO2 monitor do you recommend?

The word "track" suggests history.

I've got a https://www.amazon.com/gp/product/B0861777SL which does what it says on the box and works. I've got one in my WFH office and one in my bedroom. There are times when I've woken up from a restless sleep to see that at a higher number (especially in the winter when the house is a bit more closed up). Also the track where I can look at the history and see things "oh yea, last about 4h after I cooked dinner the CO2 went up a bit."

However, that's only the standard sensor stuff (temp, humidity, CO2).

If you've got amazon devices, I've got https://www.amazon.com/gp/product/B08W8KS8D3 ( Amazon Smart Air Quality Monitor ) which sits in my kitchen because I'm interested in other things there too.

I've had some https://milacares.com air purifiers in the house. They work as air monitors and purifiers. I had some issues with them, but they worked for a good while.

Consider if you want instant or historical data. Do you want other data too? What integrations do you have in the house with other home automation? How much DIY are you going to engage in?