Thank you everyone for your queries!
We will like to clarify that our WhatsApp stickers can be used on ALL phones including iPhones.
Just that it is available on Google AppStore but not on Apple store yet (we're working on how to get it up on Apple store).
So, all iPhones users, just grab a nice friend with an Android phone to download and send them to you. You can "add them to favourites" and use them after that. Link in comments.