I'm not sure that you can call this an "alternative" to Electron if it only supports macOS. I think the main selling point of Electron is the ability to build cross-platform GUI apps, which Shrinkray doesn't provide.
How does this compare with Electrino, which was on top of Hacker News a few days ago? <a href="https://news.ycombinator.com/item?id=14260755" rel="nofollow">https://news.ycombinator.com/item?id=14260755</a><p>And I have to agree with other commenters that this will only truly be an alternative if it could be cross-platform. It seems cross-platform support is possible (by using each OS's own browser runtime), but then you'd have discrepancies between platforms which takes us back to square one.
As far as I can tell it's just a web view wrapper for desktop. It's missing all the node features that Electron or NW.js add, which makes me wonder... why not just run it in a browser like normal?