A report by Bloomberg, confirms the existence of a humidity and temperature sensor built into the HomePod mini. Although not currently activated, the sensor could be through a software update to provide new functionality to HomePod mini via HomeKit.
The report backed up by analysis from iFixit, states the sensor is1.5 x 1.5mm HDC2010 Humidity and Temperature Digital Sensor from Texas Instruments. The sensor appears to have be placed away from the speaker’s internal components. Suggesting that it’s designed to measure external humidity and temperature, rather than internal parts.
While various third party HomeKit accessories such as the Eve Room can measure room temperature. Having this built into the HomePod mini would be convenient for HomeKit users and of course less expensive as no need for third party devices.
Like with existing HomeKit sensors that can measure temperature, users could set up automations. So based on sensor detection, a user could automate turning on a fan when a room becomes too warm.
While this is an unusual move by Apple to include hardware that is not yet enabled in the HomePod mini. It is not the first time Apple has done this. In 2008 the iPod touch had a Bluetooth chip built inside, but not activated. But Apple enabled support for Bluetooth connectivity the following year via software. So this sensor could be activated by Apple via a update, maybe as part of iOS 15 that should be announced later this year at WWDC.