Arduino IDF -> make/automake based environment

Hello out there,

I'm using the port devel/arduino18 as the basis for some small projects. I'd like to get
rid of that clumsy JAVA based IDF and move towards a more make/automake based
environment. Since I'm interested in coding for some smaller AMTEL MCUs and ESP32 and
like to digg a bit deeper than simply clicking a host base from a menu, I'm not afraid of
doing some larger basic setup if needed. But I have so far almost no experience in cross
compiling on FreeBSD and I'd like to ask whether someone out here has already done
setting up an environment based on the basic tools FreeBSD provides to develop in an
crosscompiling sense.
My IDE of choice would be Anjuta, but this is only a notice besides.

As fas as I know, the base OS for most MCUs, including my choices ESP32, ESP8266, is a
derivative of Amazone's FreeRTOS. Can the OS being compiled (cross compiled) on FreeBSD
assuming the correct compiler is at hand (which is the case, I presume since the Arduino
IDF is already working on FreeBSD)?

Thanks in advance,

Oliver