To me, direct link means a link that will send me directly to the posts on their instance (i.e. a direct link to the Star Trek website will be https://startrek.website, not https://myinstance/c/startrek@startrek.website).

Unless I'm somehow misunderstanding what direct link means here, which I might be? It seems more intuitive to me that the bang syntax would keep you inside your instance, not leave it.

And yeah, using ! is known as bang when used in this sort of context!