I use the Whatsapp Business app which allows me to be added to groups that I can’t avoid (kid’s class groups, kid’s soccer groups and my wifés family group) and to have an automatic message for people writing to me privately saying I won’t answer except if they write to me on Threema, Signal, iMessage, SMS or email.
With my own family and friends I only use Threema and Signal, even if I kind of lost or got further of some friends with my stance.
Still, I already don’t have enough time for myself, so I’m not looking to have more friends.
In my country, Whatsapp is almost everywhere, so I’m not don’t think I’ll be able to 100% leave it without sacrifizing some of my kids activities sadly..