NixOS: Intentionally breaks compatiblity with a lot of scripts and binaries due to not having /usr/bin/bash and not putting libraries in a standard location despite the fact there is still /usr/bin/env and a bunch of symlinks to things under some obscure folder in /run. It will make sure that every user has to learn Nix because you won't be able to run things from the internet without going through Nix's documentation trying to figure how to package something when you just want to run it and get on with your day.
If you enjoy packaging then this OS is for you.