I've had basically the same conversation with my sister who lives in Albania. I just want to use something encrypted like signal but she just refuses and says it's either WhatsApp or Facebook messenger. Cause of that I barely talk to her.

Here's the trick (maybe): "Don't you know that WhatsApp is owned by Meta and collecting information on your chat metadata (who you chat to, when, your contacts, their contacts)."

Tell them to get Signal. If there's any country on this planet where convincing people to use Signal is easier, it must be Germany. GMaps streetview was banned there until recently, everyone uses fake names on Facebook, if they even made one in the first place.

Surely they must be amenable to Signal