... and fire alarms? carbon monoxide detectors?

Won't those cut right through the ANC just by volume alone? A domestic fire alarm is 85–120 dB, I don't think my airpods can mute that.

And of course there will always be fringe cases. What if I go to sleep with regular foam earplugs, what if I take a sleeping pill etc. Or what if the warning sound can't be engineered to fit a ANC friendly frequency, like somebody screaming, a car tire screech behind me and so on.