As a host I can create a unique link to share with guests

 If I don't have someone's phone number, I can get a link from the app and share it on Facebook Messenger, or Whatsapp, or Snapchat, or Instagram DMs or by fax.
In the Add Guest flow, next to entering the phone number, there's an option to get a link. The person's name is required and included in the link (to help the host avoid copy/paste mistakes).