I would like to pack a Gimp ".xcf" file into a .blend file, rather than create a zip that includes this file, for example to include it in a blender.stackexchange answer via https://blend-exchange.com/. But there does not appear to be a way to link or refer to files that blender specifically doesn't recognize in something like an Image Texture node. I suppose I could "fake out" blender by renaming the file suffix, include a Text note about how to find this file, etc, but perhaps I'm missing a more direct way to pack a miscellaneous file into .blend, to be uploaded by https://blend-exchange.com/ that only recognized .blend files.
Perhaps this is for security reasons? I see this post, which might give me my answer, but doesn't give any blender product reasoning.