For me at least, it seems like development on the build system side is very slow. The relevant ticket in the CMake Repository[1] is more than three years old for a critical functionality. There are efforts to make an open interface between Compiler and Build System[2] but these are non-standard and for now it seems like there is not "one good way" to do modules. For example it is possible to do modules with the CMake MSVC Generator[3] but I can't use Ninja when working with MSVC.

[1]https://gitlab.kitware.com/cmake/cmake/-/issues/18355

[2]https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p16...

[3]https://devblogs.microsoft.com/cppblog/cpp20-modules-in-cmak...