Can a restaurant sell alcohol on WhatsApp?

No. WhatsApp bans buying, selling and promoting alcohol, whatever licences you hold. The only exception is messaging (not selling) on the API, in listed countries, to people aged 18 or over.

• The ban covers catalogs, orders and promotions. It applies irrespective of any local licence or approval.
• The exception allows messaging only, on the WhatsApp Business API, never on the Business app, and no ordering or checkout for alcohol.
• The exception covers 82 listed countries. India, the UAE, Saudi Arabia, Qatar, Kuwait, Oman, Bahrain, the UK, the US and Canada aren't among them.
• Repeat violations escalate from a warning to sending blocks, an account lock and permanent removal.
• We found no official ruling on a menu that merely lists drinks. To be safe, keep alcohol out of your catalog, orders and offers.