I have no idea how CMAKE_MODULE_PATH, CMAKE_PREFIX_PATH work,
It seems not add to search list for find_package()

1. I already have such .cmake in system. and add path to CMakeFiles.txt

/opt/ros/humble/share/ament_cmake_python/cmake/ament_cmake_pythonConfig.cmake

2. CMakeFiles.txt

cat CMakeFiles.txt

cmake_minimum_required(VERSION 3.22)
project(ProjectName)

list(APPEND CMAKE_MODULE_PATH "/opt/ros/humble/")
list(APPEND CMAKE_PREFIX_PATH "/opt/ros/humble/")

message(STATUS "CMAKE_MODULE_PATH is set to ${CMAKE_MODULE_PATH}")
find_package(ament_cmake_python REQUIRED)
add_executable(MyExecutable main.c)

(3) But get follow in error.

CMake Error at CMakeLists.txt:8 (find_package):
  By not providing "Findament_cmake_python.cmake" in CMAKE_MODULE_PATH this
  project has asked CMake to find a package configuration file provided by
  "ament_cmake_python", but CMake did not find one.

  Could not find a package configuration file provided by
  "ament_cmake_python" with any of the following names:

    ament_cmake_pythonConfig.cmake
    ament_cmake_python-config.cmake

  Add the installation prefix of "ament_cmake_python" to CMAKE_PREFIX_PATH or