I say that they were the closest, not that they were complete implementations of the vision. Firefox OS had a particularly hackable UI layer. You could install

I say that they were the closest, not that they were complete implementations of the vision. Firefox OS had a particularly hackable UI layer. You could install webpages as if they were apps (all assets stored locally), bypassing the need to get your app into a curated store. Writing new drivers in Javascript could have come later.