Code written in Rust has been shown to have significantly fewer security vulnerabilities than code written in C. Distributions like Ubuntu ship a lot of security updates, so by switching to Rust-based utils, they can reduce their workload in the long run.
I’d recommend Bazzite. It’s a gaming-focused immutable distro. The base system is an image and updates are automatic; a 13-year old might already be familiar with this kind of system because it’s similar to how Chromebooks work. It comes with Steam and Lutris preinstalled. You can install additional software via flatpak.