The same way C23 on NES, isn't C proper, rather the macro assembler K&R C used to be.
* ANSI C by 11 years (C89)
* ISO C by 12 years (C90)
https://en.wikipedia.org/wiki/C_(programming_language)#K&R_COrganisation is nothing if we do not accept individual’s role.
And good luck making good use of 6502 registers for C code.