In my part of Europe it’s all in private WhatsApp groups (one for inner family, one for friends, etc)

Unfortunately, those are also being surveilled by Meta, so the exodus from Facebook did not help. Consider Signal or a private XMPP server.

I convinced my family to try Signal, and after a month of not being able to connect despite knowing each other's numbers - silent errors - I had to apologize and join them on WhatsApp.

They all use iMessage primarily, but that's a whole other can-of-worms conversation. (Screw Apple.)