Yeah, they’ve been doing the pre-linked mega archive thing for years. It’s in /var/db/dyld. The only difference here that I see is that they’re not shipping the originals and not rebuilding it all the time. And I’m guessing the resulting archive is now sitting on a protected partition.

This thing can be taken apart, but it’s a little tricky, since it’s pre-linked. I wrote something years ago to do it, not perfect, but enough to get symbols out. (I was trying to annotate iOS stack traces.) I don’t recall if I got it working well enough to open the libraries up in hopper and poke around.