Apart from the WhatsApp example (which itself is enough to suffice, because WA hasn't changed much on positives post-acquisition), it's very much possible that Telegram is just a bunch of 50 or so people. They do not have a Dubai office afaik, but it's not that hard to get CIS talent to move to Dubai for highly paid but less than US salaries.
FWIW, I co-run a quanty multifamily investment office, and all of our employees (including partners) are expressly forbidden from listing their workplace on LinkedIn - which is the norm for family offices. We simply write Family Office and call it a day. In return, the firm will take care of you and your family for generations - extensive compensation but also other perks that you will never get in other jobs at any level.
