One of the large dependencies they call out is an excellent example: pdf.js.

There is no reason for pdf.js to ever access anything other than the files you wish to export. The Export to PDF process could spawn a containerized subprocess with 0 filesystem or network access and constrained cpu and memory limits. Files could sent to the Export process over stdin, and the resulting PDF could be streamed back over stdout with stderr used for logging.

There are lots of plugin systems that work this way. I wish it were commodofied and universally available. AFAIK there's very little cross-platform tooling to help you solve this problem easily, and that's a pity.