Apparently, it's the second most common mobile phone OS in India[1] which sounds like it's not a «no go» for everyone.

Also the question is not really “does it support WhatsApp”, but “does WhatsApp support this OS”. Which may eventually be the case if there's enough market share for that.

[1] https://www.bgr.in/news/jiophone-kaios-surpasses-ios-india-s...

That's the reason Firefox OS was dead in the water. Telcos in Europe promised there would be a version of whatsapp for Firefox OS which never materialised. A mobile without whatsapp might as well be a brick.

Whatsapp is only very big in __some__ countries actually.

Europe have free sms, so I do have friends with telegram, signal, skype, whatsapp, dumb phones, facebook chat, wire, etc., and at the the center of this crazy venn diagram, we can all discuss with sms for free. Most discussions are not group chats.

In Asia they have big whatsapp competitors like weechat. But I've seen kik used as well.

In Africa, it's also a lot of text message since they get the best coverage.

Whatsapp is definitly popular, but far from a universal.