$(find PACKAGE)/foo/bar, but ROS2

find.py

from pathlib import Path
from ament_index_python import get_package_share_directory

def find(path_string):
    assert path_string, "A non-empty path string must be provided"
    assert not path_string.startswith('/'), "The path string can't start with /"

    path_parts = path_string.split('/')
    assert len(path_parts) > 1, "The path string must contain at least two parts"

    pkg_name = path_parts[0]
    pkg_share_path = Path(get_package_share_directory(pkg_name))

    return str(pkg_share_path / Path(*path_parts[1:]))

def generate_launch_description():
    file_path = find("package/urdf/package.urdf.xacro")
    # ...