> Note that `malloc` is special in the C standard as well, and AFAIK it is not possible to implement `malloc` in standard C at all.
malloc() is usually implemented in C [0] and to be honest I'm not sure why do you think it wouldn't be? Of course you need OS API calls to actually get some memory (unless you want to operate on statically defined memory buffer) but well it's still C.
[0] https://github.com/lattera/glibc/blob/master/malloc/malloc.c