Applewatchultra has no wrist temperature.

The reason why applewatchultra has no wrist temperature is that there is not enough time. According to relevant public information, Apple released new supporting documents, adding more details of the new wrist temperature sensing function on the AppleWatchSeries8 and AppleWatchUltra models. It turns out that this function requires the user to wear the watch for five nights to detect the reference wrist temperature.