Whatsapp doesn't provide with an API to shoot marketing communications and hence we don't have a dedicated connector for Whatsapp.
WhatsApp now provides a Business API , so hopefully we should see a dedicated connector in Campaign soon. Unfortunately its in limited release and they charge for each message, but it looks hopeful.
You may have already received an answer on this but most of the clients never consume WhatsApp business API directly.
As per the best practise every organisation have ESB in place which will be the interface between Adobe Campaign and Whatsapp.
Once you receive these Rest API details you can create External Routing in Adobe Campaign and you need to create custom routing JS so that rather than calling API directly from JS activity in the workflow you can use templates as we use for mobile SMS. The user just need to whitelist the Whatsapp content and then they can create a delivery with the same content. This will ensure that we will templatise the process.