For users of Nix git-branchless is also available as a Nix flake. Flakes are only available in Nix 2.4 or newer and require the following experimental features to be set in the nix.conf:

experimental-features = nix-command flakes

Afterwards the new Nix CLI commands can be used to launch a shell where git-branchless is available using

nix shell github:arxanas/git-branchless

Users who like to be on the bleeding edge can add git-branchless to their flake inputs and use the included overlay to add git-branchless to their profile.

{
 inputs.git-branchless.url = "github:arxanas/git-branchless";
 outputs = { self, nixpkgs, git-branchless, ... }:
 let
 system = "x86_64-linux";
 pkgs = import nixpkgs {
 inherit system;
 overlays = [ git-branchless.overlays.default ];
 };
 in {
 # flake outputs ...
 # pkgs.git-branchless refers to the GitHub version
 };
}