Category theory doesn't require NULL but physical state does. Given the state of the machine as a constraint, there must be an uninitialized state of unknown or undefined (but allocated) for each type to ensure types are run as functors. I don't see why talking about the theory is useful, given the practical constraint will always provide an asterisk of *given you're working on physical memory

All types are functors in practice...which always has an element of initialization to ensure the type is defined in the memory.