Marriage on WhatsApp - Kya hoga?

Ok, imagine this - Rahul and Aisha got married over a WhatsApp video call during the lockdown. No witnesses were present, no certificate was taken, just the two of them exchanging vows. A week later, Aisha changed her mind and asks for a divorce, but Rahul claims their WhatsApp marriage is valid and he won't let her off that easily.

The question is, kya hai valid marriage under Indian law? Does the absence of a certificate and witnesses make it null and void? And what about the Hindu Marriage Act, 1955? Can Rahul claim that their WhatsApp marriage is a valid Hindu marriage under Section 7 of the Act? Or is it a case of Section 18 (void marriage) because no ceremonies were performed? The legal outcome would be super interesting in this case.