According to WABetaInfo, a website that tracks WhatsApp, the audio and video calls are now rolling out to the WhatsApp Desktop app. Unfortunately, this seems to be a very limited launch for now, with the buttons also getting beta
The new feature introduces a 'Live' tab on the navigation pane and an 'On Now' row on the Fire TV home screen, making it easier to find, browse and access live content from subscribed apps.