It would be nice to set up immutable config down to the granularity of a git commit, sharing it as a single file, and be able to reproduce that setup on anyone's machine. Instant onboarding and mirrored production (barring secrets).
There's of course Fedora Silverblue / Fedora Bootc with https://universal-blue.org/ and https://blue-build.org/ being good examples.
Recent developments have seen the creation of bootc images for non-Fedora distros too, and at this point I've seen quite a few cool arch-bootc custom images, completely customized to the author's desires. See: https://github.com/bootcrew/, https://github.com/tartaria-dev/tartaria
That being said, we used NixOS images to boot several Windows PCs of my friends into RAM to play Halo 3 multiplayer split-screen. Most of my friends were mainly confused why they could play with any gamepad they had in their shelf. They also left the event with no permanent changes to their PCs.