However, the latest WhatsApp beta for iOS 23.14.1.72 update from the TestFlight app has a feature that makes it possible to link an account to WhatsApp Web by using a phone number.

How to Get an ID & Phone Number From a Facebook Link. Facebook lets users create a unique ID or "username" that defines the Web addresses where Facebook profiles are located.

Click the "Edit" link next to Phone Number under the Notifications section. Enter your number into the field below Mobile Phone and then press the "Send Verification Code" button.