With rabbits, a common myth is that if you touch a baby rabbit the mother will no longer care for it. 9 times out of 10, the mother will return to care for the babies after they have been handled.
QNX is not a Linux distribution, normal or otherwise. QNX is POSIX compliant. That means that much of the programming interface and many of the utilities are the same. The underlying OS is very different in structure. There is little compatibility for drivers. With Linux the operating system functions as a very large monolithic piece of code.
pfSense is probably the second UNIX system to have its boot-time configuration done with PHP, rather than the usual shell scripts, and to have the entire system configuration stored in XML format. The pfSense project was based on m0n0wall, which was the first system of this type.