They are fairly inexpensive, @Andrew493. If you are keen to be in the work collection, just get one and stick it in the listing. It can sit there being useless, and you can tick the box.
I agree that the requirement to have a CO sensor, when you have all electric heating and cooking is moronic - the requirement should be if you have a combustion source you must have a CO detector, but then again, I don't get surprised by Airbnb's "Rules" making no sense.