It has potential.

One problem I found is that it wont work without turning on iCloud keychain. I dont know why that is necessary.

Another problem is that it doesnt say what is causing poor air quality. It usually says my air quality is excellent, but sometimes it goes all the way to poor, for no apparent reason. My Withings scale measures CO2, so I put it next to the Eve for comparison. The Withings CO2 level seems to remain constant.

JakeT2 about Eve for Matter & HomeKit, v2.0.1