Emacs 3rd party dependencies and user home integration can be well managed using Nix. Posimacs is a published example.
I've updated the example. It now uses nix flakes. The elisp files can be maintained as a dirty tree for happy hacking. Home manager is mainly used for the static aspects of user home integration rather than installing the elisp files read-only. I will be installing this on a Darwin machine sometime today.
Forewarning, the Emacs lisp is not marketed as good. At anything. My git tree is dirty. I mainly use the vterm integration and Rust Analyzer.
The mix of tooling is the main work output of this project so far. Appreciate pointing out any work related to the Future