No this feature is coming straight from the PDF association itself and we just added experimental support before it's officially in the spec to help testing between different sdk processors.
It's prototypish work to support it before it land's in the official specification.
But it will indeed take some adoption time.
Because I'm doing the work to patch in support across different viewers to help adoption grow. And once the big opensource ones ship it pdfjs, poppler, pdfium, adoption can quickly rise.
Part of this feature is the release of the repo https://github.com/itext/itext-eu-trusted-lists-resources which contains the trusted European certificates and is maintained and kept up to date by the iText development team. It's free and MIT licensed so go use it if you need it!
Yes, I was planning to do that in the coming weeks when I find a few hours of time.
And didn't know about the second part quite interesting, I'll look into it thank you
I use it literally everyday, not only to see the structure but also modify pdf's on the fly when I need to tests edge cases.
Stuff I do with it: Modify content streams, extract images/content, just investigate general structure of the pdf documents, remove pages, repair documents,... it's literally a swiss army knife when working with pdf's
So it might land in the spec once it has proven if offers enough value