My current favorite monospace font is Berkeley Mono1

{
  berkeley-mono-typeface = pkgs.stdenvNoCC.mkDerivation {
    pname = "berkeley-mono-typeface";
    version = "1.009";
 
    src = ../assets/berkeley-mono-typeface.zip;
 
    unpackPhase = ''
      runHook preUnpack
 
      ${pkgs.unzip}/bin/unzip $src
 
      runHook postUnpack
    '';
 
    installPhase = ''
      runHook preInstall
 
      install -Dm644 berkeley-mono/OTF/*.otf -t $out/share/fonts/truetype
      install -Dm644 berkeley-mono-variable/TTF/*.ttf -t $out/share/fonts/truetype
 
      runHook postInstall
    '';
  };
}
packages

Footnotes

  1. Berkeley Mono Typeface https://berkeleygraphics.com/typefaces/berkeley-mono/