Is it possible to remove this content after it's served it's purpose of allowing the $pdf object's items and groups to be populated?
This isn't implemented. I've put this to the backlog so we take a look later if we are able to remove these hidden text blocks from the pdf. Thank you for the idea.
In general, it would be great if jsreport offered some capabilities of making the generated PDFs more accessible.
Have you tried this extension https://jsreport.net/learn/pdf-meta ?