Are there any affordable CO2 sensors that don’t use outside air for calibration of ppm? I want to know how outside air CO2 levels change as well. Would be inter

Are there any affordable CO2 sensors that don’t use outside air for calibration of ppm? I want to know how outside air CO2 levels change as well. Would be interesting to see day to day changes and how big they are in absolute terms. (Also to show people about how CO2 levels are changing globally… without just pointing to a website of someone else’s measurements.)