It could be like MSVC_LINKER_NATVIS_FILE and accept an list of files (also from generator expressions as some library authors could add .natvis files into target_sources() usage requirement (e.g. nlohmann json: json/CMakeLists.txt at 697c7e557c84c37e88beca4eb591e4ac7b0598b8 · nlohmann/json · GitHub )
More info about linker flag:
/NATVIS (Add Natvis to PDB) | Microsoft Learn
There is related discussion in CMake Issue 26278.