The attached Code you offered is only for BME680 sensor raw feature, didn't output IAQ without BESC algorithm.
You should choose BESC library and its relative example code to fulfill it.
Recommend you to download the relative BESC library to know how to integrate into your code.
Please see the following link:
If you need, I can offer my test code based on STM32F411 platform.
alright! I will try my best. I think it would be helpful for my to have your test code you talked about..
just sending you a short reminder. A few days ago you offered to send me your test-script for measuring the voc with the bme680 (together with the BSEC-Library).