You can always have a vanilla Debian or vanilla Arch install and add things on an as-needed basis and build the OS from scratch, minimizing complexity and have them as single-duty OSes.
1. Write a config file
2. Run the command that builds the system
3. Test the system
4. (optional) Run the command that bakes the fresh system generated from the config into an image.
5. Deploy using either an image or NixOS's config based deployment tooling.