Currently for rights activists and journalist in dangerous nations (I think yours belongs to that group too) it's usually this:

VPN plus Wickr/Signal/WhatsApp combined with burner numbers linked to anonymous prepaid debit cards [connected to prepaid SIMs]. Depending on how on the ball agencies are that may also require to ditch phones every xx days, or at least take them out of rotation for few years until definitely not targeted anymore.

News organizations will also have SecureDrop setups (has anybody already hunted that?)

WhatsApp is Signal-based but closed source. Security agencies have publicly discussed the need to be able to listen in, as additional user and that would require the x joined conversation notification to be removed or not shown for backdoor entries. Obviously that's also a security risk, backdoors can be discovered by criminals too.

Will FB succomb long-term to such requests? Nobody knows because closed source. Will Google if they have an end-to-end encrypted messenger? Nobody knows...

Currently IT departments for say Reuters must order phones on which they can install a hardened android fork but also have processors which allow device based encryption, implement device based encryption. Nextdeactivate location as admin for all apps, except for the secure messenger which allows them to send distress signals. Then they must hope none of the hardware components leak any potentially dangerous data. And they need a SecureDrop admin as well.

Eventually the resource cost runs up and, of course specialized software licenses also cost. Queue maintenance cost of remotely operated updates, all of which need to be checked for security breaches again.

A local rights activists group can not even afford all of that.

AnoPhone makes it all a lot easier and that at a reasonable cost assuming they will provide updates too.