I just want to learn the low level stuff about how programs are written in C, and things like how system starts processes, how programs interact with the OS etc, (I guess that's basically systems programming ?).

It would be good to know what does make them “bad resource” in your opinion

some that I've looked up seem rather shallow and don't explain things well, what I'm struggling with is the memory allocation stuff, like what is malloc ? realloc ? calloc ?

why is Python not enough?

Python is enough, I'm happy with it; I just want to learn more.