If you're picking a distro for someone else I would not recommend a small project distro or something incredibly niche 😅
Any of the big projects should be decent. Fedora, maybe fedora silverblue or whatever their imutable variant is called, opensuse, Mint, Ubuntu, debian. (Personally I don't like some of the choices Ubuntu makes but it may still be a very good option for less technical folks)
Others can tell you which of those have the best security defaults, but to be honest it doesn't sound like you actually have particularly exceptional security needs relative to what any distro will provide. I'd prioritize something stable and user friendly- which, again, your best bet is NOT picking a niche small project or something most people have never heard of