If you have (or are willing to buy) a compatible phone, GrapheneOS is as good as it gets in my experience -- pushes the envelope of usability and security more

If you have (or are willing to buy) a compatible phone, GrapheneOS is as good as it gets in my experience -- pushes the envelope of usability and security more than any other mobile device OS yet. The sandboxed Google services compatibility layer (using device profiles) lets you have your privacy cake and eat proprietary apps when you need them, too.