On mobile there are various options. The apps which are likely to be most secure are ones which have end-to-end encryption enabled by default and which can also be onion routed via Orbot. End-to-end encryption secures the content of the message and onion routing obscures the metadata, making it hard for a passive adversary to know who is communicating with who.
There are parts of the world, like 80% of it I guess, where secure=anonymous.
Encryption does not hide your identity, necessarily, as far as instant messaging goes. Different aspects.
80%?! What magical planet are you from? This is complete nonsense, put some sources because this is a complete lie. Nobody will believe you without proof.