Otpless is providing WhatsApp login button

Otpless.com is giving the option to create a WhatsApp login button on our WordPress websites.

Is it possible on discourse websites also? How (not)?

Yes, It could be possible using https://WAuth.in

In fact Wauth can also be used to implement Login With Whatsapp buttons on website / mobile apps as an OTP-Less alternative to traditional SMS OTPs.

They are offering 2 Months, Unlimited FREE Trials too.