Sweet, I've been wanting to create an OS on a RasPi, and your project just made it easier. Thanks! I was going to use Electron, but I guess Chromium is good too. I'll have to change some things to make it work with my FeathersJS app.
https://github.com/Lerc/notanos
There's a quick runthough in this video.
I was inspired by Firefox OS some time ago and found that I could access various parts of the filesystem via nodeJS. My plan is to run my node app and launch Electron fullscreen when the Pi boots.