I would not say that GCC is more focused on C. Also in GCC there is a lot more effort going into C++ than C. C is generally neglected, which is sad given its importance.

GCC's support for C23 is essentially complete. Clang is mostly catching up, but features I need that I am missing are storage class in compound literals and tag compatibility. It is also sad that Clang does not implement strict aliasing correctly (it applies C++'s rules also in C).