I mean, exactly how invasive are default operating systems? (Like Windows, Mac, Chrome OS, Android, iOS) Do they log your keystrokes, log passwords, capture screen, upload your photos, videos, or audio? (Assuming you aren’t a target of government) Is it even possible for the average person who doesn’t feel comfortable messing with installing operating systems to have any privacy?
There are user friendly options if you’re willing to use them. There’s /e/ foundation’s Murena phone that you can buy. It’s based on LineageOS for microG with a custom launcher much like iOS. It works out of the box, no tinkering. There’s also GrapheneOS that has a web interface for installation. It is only for Google Pixel phones and takes a different approach to privacy than LineageOS for microG. They both work in protecting your privacy. As far as computer OSes, there are many “easy to use” options for the novice - PopOS & Linux Mint are the best two that come to mind.