Is there anything stopping us from adding ASM to the list of languages that CMAKE_<LANG>_COMPILER_LAUNCHER supports? ccache apparently has first-class support for ASM (see support table), so being able to take advantage of that would be desirable.
I don’t think there is anything fundamental. Projects can always not set CMAKE_ASM_COMPILER_LAUNCHER if their launcher does not support ASM.
There are multiple ASM${ASM_DIALECT} flavors of ASM. We’d need to decide which ones can get it.