There exist inexpensive real co2 sensors, e.g. https://www.sparkfun.com/products/22396 . Datasheet says only updates every 5 seconds & 60s response time “for achieving 63% of a respective step function”, which I guess is what parent comment means by “They’ll likely be extremely slow”.
Probably worth searching e.g. digikey for sensors with faster response time.
description of (network, dataset) for LLMs ?= model that takes as input index of prompt in dataset, then is equivalent to original model conditioned on that prompt