Will it translate to yaml for toolchains that want that?
I'd be delighted to have a high-level IDL that gave the same sort of thing that CORBA IDL gave us 25 years ago -- schema and stub generation for multiple languages.
It doesn't have to be the NULL macro, which is correctly defined as plain 0.
The literal 0 is treated specially, so this could indeed be one of those 'turns into a weird bit pattern NULL pointers', if such a thing existed in the wild anymore.
But you're correct in that there probably haven't been any since the turn of the century or whenever the last Univac mainframes got turned off.