The Prompt for File action (v8+) prompts for a selected file or folder and saves the path into a variable.
You can prompt for an existing file or folder, or for a new file or folder.
For a new file or folder, you can specify the default file name.
For an existing file, you can specify the allowed file types with a space or comma separated list of extensions or Uniform Type Specifiers such as public.image
.
You can (v9.0+) specify the default directory in the action.