You don't get quite this level of ambiguity with standard C, since it does not provide objects (in the object-oriented sense) with constructors, in contrast to C++ that is used in the Arduino environment (in C++, initialization order of global objects is indeed unspecified, inviting subtle bugs to occur).

However, many common C compilers provide methods to declare functions to run at initialization time, e.g. gcc's `constructor` attribute, opening this rabbit hole also for C programmers.