This looks great. And Sketch is incredible. I wish there was something like it available on Linux, or I could run it on Linux somehow. Seeing how important a tool it's becoming to web design makes me uneasy as it's shutting out my ability to do anything design related :/
I keep an old Mac around for exactly this reason. However since version 43 they've switched to a new file format offering "more powerful integrations for third-party developers".
The new format is a ZIP containing a bunch of JSON files per page, so maybe someone will come up with a cross-platform viewer or similar.
Unfortunately, there's still a bunch of internal Sketch APIs we have to call, though radically, radically fewer than in the version of react-sketchapp pre-Sketch 43.