Unfortunately, it’s not looking too promising so far. While I am awaiting a Raspberry Pi so I can better compare data from the devices historical data on Home Assistant, just glancing at them a few times every day tells me that they have very low reproducibility.
Here are readings from my three devices at two different times. While it appears that the middle one might have been calibrated differently, they’ve all been running for the exact same length of time in the same conditions. Furthermore, the middle one now reads similarly to the one on the right, and the left-most Alpstuga has begun reading 20-40% lower than the other two. They seem to randomly jump around, and they often exceed the ± (100 ppm + 10% of reading) accuracy specification the sensors have.
Right now, my right-most sensor is showing 837 ppm, the centre shows 1123 ppm and the right shows 1089 ppm. Unfortunately, it’s quite hard to get images of all three devices - the images tend to come out like this:
This feels like a somewhat similar issue to what the Atmotube Pro 2 with the STCC4 sensor had, but I await my Raspberry Pi for further comparisons!