Very sceptic that RoR can obtain/interact with the browser push notification API as I stated in my example. You'd have to come up with glue JS code yourself, and that is where it gets messy. Pushnotifications just being one of many APIs that are client-only (and again please, if you don't need to interface with those APIs, then you might not need an SPA in the first place).

Just because "remote forms" have forms in their name it doesn't mean that they are conceptually the same thing. They are not, so obviously they can achieve those things, but they are built with js.