the current show-stopper issue is that Typst can't insert PDF as figure[1], this makes a lot of scientific publication workflow impossible.
The thing is, inserting PDF for just the PDF export would be quite easy. The issue is the other export targets Typst supports (SVG and PNG) as that would require some form of rasterization / a full blown PDF engine written in Rust without C-bindings because of the web app and that simply does not exist yet.
And the developers are hesitant to just add features for one specific export target which I get.