Tried to find more info about it but the Nixpkgs manual has only two results (regarding Emacs), this thread is about poetry2nix, and the wiki example above is regarding Xfce.
“Scope” as a term is also not explained in the Nixpgks manual but I assume that the language packages also belong to a “scope” (e.g., under Haskell, Python, Erlang) so overrideScope' can also be used for that.
Or not. Haven’t looked at the source yet, and I thought I would ask here first. Thanks!