Apple keeps the encryption keys and they can access all of your messages, if they feel like it. signal is encrypted by default and just saves when you created and when you last logged in to your account.
on the one hand i agree: trustworthy does not mean privacy. but on the other hand: ai does not necesaarily mean privacy invasion (though experience might tell us otherwise)
well there also does not seem.to be a multi billion dollar corrupt gang of geniouses behind it. what you do with your data is up to you but im just saying that we can be happy that there are options out there.
so gnu/linux is just a quick lernel rewrite away from total market domination. excellent!