Actually, the entire new line of Ikea smart home devices are really fantastic. They're all equipped with Thread radios and use Matter, which means they integrate directly into Apple's Home app without needing a separate hub.
And they're dirt cheap. I haven't been able to find another Thread/Matter button for less than $20, but Ikea's is like $6.
Checking it out locally, they go for 30€ here. That's cheap! I remember just a few years ago such products costing 80~100€ if you wanted it in a polished product (not a sensor from China, needing to write code to read it out). Is this a direct CO2 measurement, not one of these that uses VOC as a proxy measurement?
The part from the post that answers your question is this:
The sensing platform used is a Sensirion SEN63C, which uses a STCC4 for CO₂ measurements. Unfortunately, this is not an NDIR sensor. Instead it uses less accurate thermal conductivity sensing. This allows building smaller/cheaper sensors, but it depends on the input of the temperature/humidity sensor, because e.g. humidity influences measurements. Also, the sensor relies on the air mixture being 78% N₂, 21% O₂, 0.93% Ar, 400 ppm CO₂ and will stop giving accurate readings when this composition changes (modulo CO₂). The operating conditions are also more limited than most other CO₂ sensors (10–40 °C, 20–80% RH).
From what I could gather and what is also mentioned in the conclusion is that the sensor is fine to get a general feeling of the CO2 trends, but that you're better off getting a better sensor if you care about exact values.
Oh, that's a shame :(
Similar to when I bought a TVOC sensor that claimed to have CO2 as well. Until I realized it was eCO2 which is pretty much useless because it just guestimated based on TVOC counts.
ALPSTUGA
My house stays around 800-1000ppm CO2 all the time The HVAC is poorly designed in my opinion.