(cross-cutting) Author using Nix/NixOS hits friction with monolithic deployments across multiple project repos—constant redeploys to single DigitalOcean droplet. Solution: systemd-nspawn lightweight containers eliminate redeployment cycles while maintaining systemd integration (registers with systemd-machined, shows container services in systemctl --recursive, auto-resolves container names). Enables parallel project iteration without full NixOS redeploy overhead.