I installed hacky ChromeOS to my grandma’s laptop a few years ago. She never had issues with the OS itself, rather hardware issues. It’s easy to learn and ChromeOS is literally just a web browser, it’s not even useful for anything else. Though I would recommend you install something like Fedora Silverblue, Kinoite, or a distro from UniversalBlue instead. Container based distros are secure and hard to break.
Well, NixOS is pretty easy to install using their graphical installer and it has one of the largest package repositories. It has basically everything you could need.