I did a small test in C.
Code:
  char *path = getenv("PATH");
  if (path)
    printf(path);
  printf("\n");
produced the following
Code:
[root@gp2x dev]$./test2
/sbin:/usr/sbin:/usr/local/sbin:/bin:/usr/bin:/usr/local/bin
getenv() definitely works on the GP2X. I don't know what FPC might be doing wrong.