Yes, you can wear the sensor in a sauna, however the manufacturer says that the temperature range of operation for the sensor is between 10-45 degrees C.
A few things to note:
While in the sauna, the CGM might fail to record readings as the sensor can turn off at a high temp and turn back on when it returns to a normal temp
You may see a spike during the sauna session
When you're sweating, it can be easy for the sensor to be bumped off, so take care and wear a patch over the top
If your sensor falls off when in a sauna, we unfortunately can't replace it for free, so please take care if using saunas.