WhatsApp has nearly always been available on iOS, but not on iPads. However, as these tablets come with SIM-enabled variants, some users would probably like the option. The app's developers may now be working on a new beta that is optimized for these Apple slates.
https://www.notebookcheck.net/WhatsApp-may-be-preparing-a-version-of-its-app-for-iPad.416093.0.html