Building ESP8266 RTOS Project

I’d like to build the ESP Homekit project here (https://github.com/espressif/esp-homekit-sdk) which uses ESP8266 RTOS. Is there a way that I can easily use PIO to build this? To build the examples, do I have to do anything special like change folder structure, etc?

The example project I’m trying to build uses a Makefile. Is there a way to tell PIO to use the local Makefile to start the process?