API using laravel jetstream and inertiajs for 3rd party

I know that jetstream uses sanctum for authentication, but how does 3rd party application access the api ? For example I have:

web

Route::resource('posts', 'App\Http\Controllers\PostController');

PostController

public function index()
{
    return Inertia::render('Post/Index', [
        'posts' => Post::all(),
    ]);
}

This works fine for the application itself but how does for example Postman access the api? The docs explained to uncomment several things in the config Jetstream : https://jetstream.laravel.com/1.x/features/api.html.

The confusing part for me is, the index() method is returning an inertia page, so if postman/3rd party access it wouldn't they get the page as a response?

So do we need to make a separate method that returns only the data for 3rd party apps like:

public function index()
{
    return  Post::all();
}

and should it be placed in the api routes instead of web routes ?