{ config, ... }:
{
  config.packages.capybar = {
    systems = [
      "x86_64-linux"
      "aarch64-linux"
    ];
    package =
      {
        fetchgit,
        lib,
        libxkbcommon,
        pkg-config,
        rustPlatform,
        seatd,
        udev,
        python3,
      }:
      rustPlatform.buildRustPackage {
        pname = "capybar";
        version = "unstable";

        src = fetchgit {
          url = "https://codeberg.org/natty/capybar";
          rev = "797c67466e9bd95b1494dd5ec5e57b8754b05f8c";
          hash = "sha256-4ImDpqRZ5to+FzwAw8lZwPYN4nG5q697Pya5aw0Bqc0=";
        };

        nativeBuildInputs = [ pkg-config ];

        buildInputs = [
          libxkbcommon
          seatd
          udev
          python3
        ];

        cargoHash = "sha256-MMTUdXcBfUQKRjgDZZsaVH/vow/AfPJbR7bGGgSW/wA=";

        meta = {
          description = "";
          homepage = "https://codeberg.org/natty/capybar";
          license = lib.licenses.mit;
          mainProgram = "capybar";
        };
      };
  };
}

~/code/gitgay/fur fsh > nilla run capybar
🍦 Nilla  INFO  Looking for project at ./
🍦 Nilla  INFO  Checking project for value
🍦 Nilla  INFO  Building package capybar
trace: evaluation warning: 'system' has been renamed to/replaced by 'stdenv.hostPlatform.system'
error: builder for '/nix/store/7qr5m0djzij42k1alr174snqc1gamqsm-capybar-unstable.drv' failed with exit code 101;
       last 25 log lines:
       >       code: 2,
       >       kind: NotFound,
       >       message: "No such file or directory",
       >   }
       >   STARTING A FULL BUILD
       >   HOST: x86_64-unknown-linux-gnu
       >   cargo:rerun-if-env-changed=CLANGCC
       >   cargo:rerun-if-env-changed=CC
       >   cargo:rerun-if-env-changed=CLANGCXX
       >   cargo:rerun-if-env-changed=CXX
       >   cargo:rerun-if-env-changed=OPT_LEVEL
       >   cargo:rerun-if-env-changed=SKIA_USE_SYSTEM_LIBRARIES
       >   cargo:rerun-if-env-changed=SDKTARGETSYSROOT
       >   cargo:rerun-if-env-changed=SDKROOT
       >   cargo:rerun-if-env-changed=SKIA_NINJA_COMMAND
       >   cargo:rerun-if-env-changed=SKIA_GN_COMMAND
       >   Probing 'python'
       >   Probing 'python3'
       >
       >   --- stderr
       >
       >   thread 'main' panicked at /build/capybar-unstable-vendor/skia-bindings-0.86.1/build_support/skia/config.rs:374:9:
       >   >>>>> Probing for Python 3 failed, please make sure that it's available in PATH, probed executables are: ["python", "python3"] <<<<<
       >   note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
       > warning: build failed, waiting for other jobs to finish...
       For full logs, run 'nix log /nix/store/7qr5m0djzij42k1alr174snqc1gamqsm-capybar-unstable.drv'.
🍦 Nilla  ERROR  Package has no outputs