Google uses Signal protocol to handle E2E for RCS communication:
Google SAYS they use the Signal protocol.
Without open-source applications, you have to trust these companies to do the right thing when they can track you and make money from it in every single step of the way. Same goes for Meta with Whatsapp.
When I first tried to install Arch, I gave up when I got confused with the documentation for an encrypted install.
But since I’ve discovered archinstall, it’s a dream to do and arguably faster to install than other distros.