Any initiative to introduce small and cheap CO² sensors?

Is there any initiative/progress for developing CO² sensors small and cheap enough to integrate to smartphones and similar common "consumer electronics"( watch, tablets, home assistant)?

Here's why I'd like to support such: In short firmly believing the measurement≈attention heuristic[0] this promised a massive improvement for solving climate crisis.

Bit longer, the motivation is as follows: Meaningful volume of people care about fitness, indoor atmosphere is a big affecting factor, checking the measurement gives mental anchors to those careful for own conditions, makes many aware of the local and time changes in CO² levels, which I tend to conclude leads to better actions.

Detailed analysis: According to Wikipedia and some practical research of mine and friends we can see the price of CO² measuring equipment in $20-x00 range and is 1+ cm usually. This limits the usage for special purpose monitors and unsuited as addition to any smart assistant hardware.

[0] https://twitter.com/danspena/status/256053912279343104?t=7ZEBJKP70CgLaGytMUnI8Q&s=19