Are there any hotels that install smoke-sensing and fire-fighting facilities in guest rooms and bathrooms?

yes, there are toilets in hotels in Singapore. When the fire smoke level reaches .65 ~ 15.5% ft, the alarm concentration is slightly different for different manufacturers and models of smoke detectors.

The principle of smoke concentration alarm is photoelectric induction. When smoke enters the smoke detector, the smoke changes the light intensity sensed by the smoke detector, which then triggers the alarm.