Comment by pona-a
How so? I'm writing this from an Fedora Sericea, which is Silverblue but with Sway instead of GNOME. Atomic Fedoras solve only package hysteresis (your package manager being unable to reproduce the intended system state because of unaccounted for changes) by generating the root file system with OSTree. It has nothing to do with sandboxing the applications themselves.
It does in the sense that all the applications you install will be via flatpak, so they get sandboxed that way. Of course it depends on how locked down the sandbox is configured for each of those applications.