I tested the C code to an extent against the pimoroni python library and the results seemed very similar, so it seems to me the sensors are high temperature and low humidity which makes sense as there is a heater on the chip and as you said the mounting direct on gpios not good…
The air quality gas readings seem good as long as you keep polling the sensor every few seconds, and a fixed compensation on temperature and humidity will work well enough for me. But seems a chip to buy more for the air quality sensor than if you just want temp/humidity which a cheap chinese bme280 will do.
There is a C example using the Bosch C library on github that the link to is in the other thread on support forum.