This is absolutely doable. I have ours setup to turn on when co2 roses above 800ppm and then turns off when it goes under 650ppm. I choose those numbers somewhat arbitrarily but they seem to be good enough.
There are plenty of sensors out there you can use. My sensor is an iqair visual, but that is just what I had on hand when I went down this path -- if starting from scratch I would probably look for a cheaper CO2 only sensor.
On Christmas morning, when the motion sensor in the hallway next to the living room is triggered, it slowly turns on the Christmas tree, turns on the stereo, sets the stereo volume to 0, starts a Christmas music playlist, then slowly turns up the volume.