Would it be possible to use this on the server to create complicated PDF files for download (react -> sketch -> pdf), without using something like this current process (react dom -> html, css -> phantomjs -> pdf)?
Yeah sure - the caveat is that you have to run it on OSX rather than Linux. We have a bunch of Mac Pros & Mac Minis laying around the office doing CI funtimes.
I also hear whisperings of a react-pdf renderer but I haven't seen it