Pretty sure the Netatmo Indoor one does CO2 - https://www.netatmo.com/en-gb/aircare/homecoach
Only their Thermostat has official SmartThings support, but looks like there are community DHTs floating around - Netatmo Healthy Home Coach (Air Quality Monitoring)
There are other solutions out there, but none that I know of off the top of my head that work with ST.