Feature Request: download [gallery] images instead of post attachments

Hi,
I am desperately looking for a plugin that can identify the images contained in a [gallery] shortcode on a post/page, and offer a ZIP of those images to the user.

Your plugin comes closest to this. Except, your plugin identifies the images that attached to the post, and offer those as a download. But sometimes, a gallery present on a post will contain images that are either not attached to this specific post, or not attached to any posts.

Is there a way to add a way to add this option in your plugin?
And then perhaps in the functions.php we can identify if we would like to offer the download from the attachement files, or from the [gallery] shortcode? + if we choose [gallery], then perhaps the DOWNLOAD button would appear directly under the [gallery] instead of at the end of the post.

https://wordpress.org/plugins/zip-attachments/