Matrix fits the bill. It's federated - you can have rooms and conversations across homservers seamlessly today. There are several implementations for both server and client.

It's still a way to go to be 100% though; for example portable identities - right now your user account is tied to a specific homeserver, yours or somebody elses. And first class tor (or i2p?) support with enough federation over either. Performance of synapse and elemnt, spoecifically, are also pretty poor.

I really think it's on the right track though - all my reservations for matrix in its current state have been recognized by the maintainers and are on the roadmap.

That's what I thought as a european in the beginning of this year.

But in a matter of weeks, all of my closest friends and family members downloaded Signal. I was able to convert some people by myself by just deleting my WhatsApp account.

Last year I had a phase where I wanted to ungoogle/uncloud my life. I never thought that I would be able to delete WhatsApp for the same reasons you mentioned. Turns out, most people don't really care about installing another messenger, if they do, I just write them via SMS.

I now chat 90% on Signal, the other 10% are split between Threema, Telegram, SMS and Discord.

One thing that might be hard to overcome here in SA (Peru) is that many providers seem to have data caps, but will provide whatsapp (and facebook) access for “free”, even if you are out of data (the services seem to still work exclusively). I’m not sure what deal was made (or if the providers are doing this out of the goodness of their hearts..?)- but the same would probably need to happen before you see a migration.