Thanks to u/iap-scrivener on Reddit for their post in this Reddit thread.
The link, though, is broken; I couldn’t immediately find a way to link from one Scrivener (3.3.1 on 13.4) document to a specific portion (ideally, say, a Heading) in another (Scrivener) document.
Here is an updated link to that topic. There has been a fair bit of discussion after that post as well, which showcases some different approaches based on these core ideas, from the community.
You’re welcome! I’ve done a little shuffling of its content, as I have realised in retrospect that some of the practical examples ended up getting introduced before all of the core ideas for linking. It should hopefully flow a bit better now, showing that idea, and then building on it with the examples.