We have integrated the invitations module with WhatsApp business.
It works like this:
member goes to whatsapp invitations page and clicks on one of the template messages about the site activities.
The template message goes to user's WhatsApp from our business number.
It has the icode and link of the invitations module which refers the member.
Member forwards this message to his/her friends.
Friends click on the link:
here we have a trick
it adds a greeting message and profile picture from the referring member to the registration page.
I also added this greeting to email invites.
Just an other idea for professional module developers.