uBlue Bluefin or Aurora. Tested and approved. I moved my dad on Bluefin one year ago, no issues, it just works for his use case (90% of the time in a browser, light photo editing in Krita, some text editing). No maintenance, no updates, no actual knowledge needed as a daily user, just a single reboot once a week to boot the freshest system image.
And more importantly, it keeps on working despite his talent for fucking up every single piece of software he lays his hands on.