I think measuring CO2 is mostly only useful as a proxy for how well you are ventilating (which is correlated to the health of your air unless outside air is filled with ie small particles or smog), and when you measure 800 ppm it is more than adequate. 800 is not doing anything to the body (that we know of).

Do you want to use chemicals and devices that make the climate problem worse just to lower the CO2 concentration in your personal space? Sure it’s a small effect but not something we can all do.