how-to-export-package-level-types.md

These are not the droids you're looking for.

Try these instead:

• https://github.com/coolaj86/test-case-tsc-exports
• https://github.com/BeyondCodeBootcamp/js-with-types-jsdoc-tsc-starter

main.js

/**
 * @param {import('foo/types.js').Foo} foo
 */
function bazzer(foo) {
  return {
    baz: foo.name,
    qux: foo.flavor,
  };
}

node_modules.foo.types.js

/**
 * @typedef {Object} Foo
 * @property {String} name
 * @property {"vanilla"|"chocolate"|"strawberry"} flavor
 */