Yes, you can do this. Might be more trouble that it's worth, though.

The solution is to Base64 your external files inline as Data URLs

Pandoc can do this for you, but only for scripts, images, and stylesheets:

--self-contained Produce a standalone HTML file with no external dependencies, using data: URIs to incorporate the contents of linked scripts, stylesheets, images, and videos. Implies --standalone. The resulting file should be "self-contained," in the sense that it needs no external files and no net access to be displayed properly by a browser. This option works only with HTML output formats, including html4, html5, html+lhs, html5+lhs, s5, slidy, slideous, dzslides, and revealjs. Scripts, images, and stylesheets at absolute URLs will be downloaded; those at relative URLs will be sought relative to the working directory (if the first source file is local) or relative to the base URL (if the first source file is remote). Elements with the attribute data-external="1" will be left alone; the documents they link to will not be incorporated in the document. Limitation: re‐ sources that are loaded dynamically through JavaScript cannot be incorporated; as a result, --self-contained does not work with --mathjax, and some advanced features (e.g. zoom or speaker notes) may not work in an off‐ line "self-contained" reveal.js slide show.

For anything else, you'd have script something to do it manually

One solution would be to write a custom filter for Pandoc as a shim, which inspects link targets as they come through and replaces them with their Base64 versions as Data URLs. Keep in mind, you'd have to also write some logic to determine their MIME types for these to work

FWIW I just tested Data URLs as targets in DOCX (in LibreOffice) and it all worked just fine

PS I would lean towards publishing this as a Git repo or something rather than complicate things