I will give a try with Signal, thanks for your suggestion.
I read now about end-end encryption and it looks like WA is better than Telegram.
However I feel the battle to be private on social is kind of lost one from the beginning.
The golden rule is not to use socials for sensible stuff. Period.
Since last weekend, I am google free (no gmail, no gdrive, ect...) and I discover how much features and cool stuff we can do outside the golden google cage... yes I had to take some $ out af my pocket (buy a domain and Fastmail account), but it was worth every penny. Finally I have a real email account and full control on it.
Interestly enough I jumped off the google boat for privacy reasons and then I discover that for me the most important point is the functionality / feautures that I was not aware when I was a google "slave".
Telegram until now is fantastic because of the user interface, portable and light client, and nice unique features there. If Signal can do better I will be there.
Thanks for your input.