That’s the one that did not work here at all. This is after running the device for more than seven hours:
The upper value is from a probe resting in free air inside the enclusure (cross-checked at various spots with only very minor variations), the lower one comes from a probe nested between the filament strands and, hence, measuring the actual temperature of the material. After having the moist PETG in there for 24 hours, the weight of the spool was exactly the same as before, so no moisture has been extracted at all. Just as expected with such low temperatures.
Immediately thereafter, I transferred the filament to the new, fan-equipped Sunlu S2. Temperature readings after about 6:45 hours:
I weighed the spool upon completion of the 8-hour-cycle and it already lost 3 grams, then one more after a total of 24 hours.
I contacted Fixdry support with this data and asked whether my device is defective. The answer:
„We would like to take this opportunity to explain our filament dryer’s unique features. Our dryer utilizes PTC heating technology and a fan to effectively dry and dehumidify your filaments. The hot air is blown into the dryer from the outlet, and then the fan circulates the air to ensure even distribution of heat. Therefore, due to the temperature difference at different positions inside the dryer, you may notice slight variations in the temperature compared to the set temperature. However, this is a normal occurrence and does not affect the dehumidifying performance of the dryer.“
Well, needless to say that I returned the Fixdry for completely lacking the promised performance and kept the S2 instead… 
I use the 2023 S2 for actually drying the filament and keep the older, fan-less S2 to be able to print from one pre-dried spool while drying another one in my primary device. Works quite well for me. However, to get back to the original post: I have not attempted to dry any filament requiring higher temperatues than 70 °C yet. Therefore, I cannot make any promises regarding the performance of the S2 with such materials.
Edit: In my experience, the fan-less S2 is perfectly capable of removing just as much moisture as the new edition (provided you keep the lid open by a few millimeters). The difference is merely in the time required to do so. I have not done a thorough test, but I’d estimate it needs about 30 to 50% less time for the same result.