First of all that only works with vectors, but I want operator overloading to also work on things like matrices or custom types (for example quaterions, or a symmat3 struct that represents a symmetric 3x3 matrix using only 6 floats).

Additionally, for efficient math code you often want vector / matrix types in AOSOA fasion: for example Vec3<Float8> to store an AVX lane for each X/Y/Z component. I want vector/matrix operations to work on SIMD lanes, not just for scalar types, and Zig currently can't support math operators on these kinds of types.

Vectors in Zig are SIMD types. Vectors in games are probably algebraic types. Using SIMD for the latter may not be that useful if 1) specific elements are accessed frequently 2) transformations involve a different operation happen on each element.