Would you prefer one of the alternatives that also gives you cross distro packages that work, but with stronger security guarantees and developer ethos?
You can install nix. Does not give you sandboxes like flatpak unless combined with other tools like firejail or nixos-shell, but at least nixpkgs-unstable is one of the most up-to-date package managers out there.
snaps are the one I'm most familiar with, which provides sandboxing wherever possible, automatic updates, and a permissions system where I can do things like deny Firefox access to my webcam. And is available on a number of Linux distributions.