alt Hacker NewsIt only works for WhatsApp if you have Backup to Google activated[1]. I once tried to work with backuped files from my old phone and it didn't work. (Older tutorials indicated that it once worked, though.)
[1] There was a time WhatsApp had a nag-screen if you hadn't Backup to Google activated. So I guess most people would have eventually caved.
That nag-screen is still there, it pops up roughly every three months for me (though not on my primary phone, Whatsapp won't get anywhere near that one).