NixOS

The description on nixos.org is about Nix, the tool NixOS is built around: “a tool that takes a unique approach to package management and system configuration.” It states three properties:

• Reproducible — Nix builds packages in isolation, so that a package that works on one machine works on another.
• Declarative — it makes it easy to share development and build environments.
• Reliable — installing or upgrading one package cannot break others, and you can roll back to previous versions.

The Nixpkgs collection is described as offering over 140,000 packages.

For fleets of devices, the appeal is that the whole system is described in configuration and can be rebuilt and rolled back. The trade-offs are a distinct learning curve and a larger base than minimal systems; supported architectures are not listed on the page consulted, so check before choosing hardware.