I've deduced that if a C compiled function references another C compiled function at export, the sub function is exported to .c with it.
This represents a large part of the functionality I was inquiring after, but it does raise further questions.
For example, if I compile functions A, B, and C, C and B both using A; and export C and B to .c separately, is A duplicated?
This could yield an angle of attack for the broader question of 'how to link in C from compiled C', but I don't yet see it.