Which smartphones have a built-in thermometer or infrared camera?
There have been a few smartphones created that do have internal sensors and infrared cameras built-in for measuring temperature. These models include: Huawei Honor Play 4 Pro comes with an Infrared Temperature Sensor (IR) to measure the temperature of both humans and non-living objects.    The FISE 4G phone comes with an integrated infrared thermometer.  The Blackview BV9700 PRO comes with the ability to measure indoor air quality and measure ambient temperature and humidity levels.