Would it be practical to build a 10 sensor device ?
What specific sensors are you are thinking of?
These are the chemicals I am thinking about; Ammonia, Carbon monoxide, Methane, Oxygen, Ozone, Chlorine gas, Hydrogen Sulphide, Carbon Dioxide, Formaldehyde , TVOC / VOC.
I came here to the forum to see if there was any discussion of having an O2 sensor. I’m a little surprised that this is the only discussion that I find. But I like the way that you think. I would buy that sensor unit in a heartbeat.
I haven’t heard them mention any plans for officially supporting an O2 sensors. The Open air Max can have an O3 sensor.
The great part of open source is that if you want to out in the effort, you could add one and customize the code to support it
I found this sensor that works with Arduino
https://wiki.dfrobot.com/Gravity_I2C_Oxygen_Sensor_SKU_SEN0322
I use ESPHome on my devices and someone added unofficial support for this module