While it is true that the core WiFi code is not open source, the ESP-IDF is significantly more open than anything else on the market today. This is not to say

While it is true that the core WiFi code is not open source, the ESP-IDF is significantly more open than anything else on the market today. This is not to say that Espressif is the bee's knees. I personally wouldn't use their hardware in production. But by making their product easily accessible, and much of the source code open, they have made it easier for white hats to raise security issues.