It would be nice if push notifications would work outside the browser. Also for Android or IOS. If this would be possible mobile apps would not longer be necessary.
I don't know exactly what mechanism they're using for the mobile app, but I'm pretty sure their push notifications are powered by Firebase or something similar... maybe Arsalan can tell you more.
I know, but it wouldn't take much to implement an existing push API like Firebase or similiar providers to realize that for the website, that's the only point for an app at the moment.