Beside Nix and Scheme the main point is that an OS is defined, so easy to replicate, easy to change and revert, ... with just few text files, this is a thing ALL systems MUST have since DECADES instead of remains back at the 80s like most system are, offering at maximum some third party tools to replicate (if they work properly) with a far bigger work from Fog to Ansible. Infrastructure as Code is simple and can be done by anyone with Guix/Nix and that's the real point. Build a custom ISO to quickly deploy any personal system or simply give it to a third party with a preconfigured reverse ssh / rustdesk is a VERY nice and useful ability.
Unfortunately most of the current development goes in wrong directions for the humanity (containers and so on) because those routes are needed for commercial purposes, and that's make a large slice of the current sorry state of IT.
An open suggestion: try to think about what we have in tech terms today, imaging the present with an IPv6 global per host, a common practice for anyone to have a family domain name, a personal one for adults, subdomains for their hosts and a desktop centered model, where any home have a homeserver to allow sync data between personal and friends hosts. Did you realize that we ALREADY have all the tools, just lacking knowledge and interest? Deploying such infra with systems designed like Guix/Nix allow is something a casual domestic power user can do at home. Something all high school students can learn, understand enough to became netizen of a new old internet. Try to imaging how much we miss just because most if the IT development is directed by few giants who know and many "sheep" who do not know nor care to a point even many techies fails to imaging what we can really do.