If you have a fleet you might want to check out NixOS and Hydra. There is someone building nix pkgs for ARM/RPi not sure what is the current status... Just keep

If you have a fleet you might want to check out NixOS and Hydra. There is someone building nix pkgs for ARM/RPi not sure what is the current status... Just keep in mind that the learning curve is steep for NixOS, but the entire thing can be automated. Broadly speaking if you want security you need to compile and distribute your own packages.