I have a whatsapp because my dad wanted to be able to call me without international long distance fees. He's called once and I get endless amounts of spam. I'll be seeing him in a couple of weeks, and I can hopefully switch him to LINE (what everyone uses here) and get rid of this app for all and get the last cancer of Meta out of my personal life.
WhatsApp is fundamentally bad and anti-consumer because it is proprietary. When people are not allowed to understand, change and redistribute the source code, the people will ALWAYS be milked and abused in some way. Trust me. LINE is also closed source and unfree, so it would only be a matter of time until that company fucks you up and you want to switch to another messenger.
The most popular open source/ free messenger would be Signal. Conceptually the most promising one in my opinion is SimpleX Chat, if you want to be a bit more adventurous
No one I know is going to change to those. LINE also has other business stuff built in for interacting with companies (customer service for my massage place, my dentist, etc.) In an ideal world, sure, but it isn't going to happen.
I have a similar issue but I am able to use SMS for those few people, most of them are relatively easy to convince of Singla in my experience, it's as easy as it gets, basically whatsapp in secure!