So, I've written this small extension to #guix lately: https://framagit.org/tyreunom/guix-home-manager
It's a configuration manager for user home directories. It makes your $HOME read-only and your configuration is fully declarative, programmable and stateless. Like dotfiles repos, but with more features and better reliability!
It's very experimental and a bit drastic, but it works and I find it exciting 😀