Let me provide the devshell so I can see if you can reproduce it.

{
  description = "Super simple starting point for Polar development flake";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/staging"; # Change to staging,  TODO: https://nixpk.gs/pr-tracker.html?pr=453690
    flake-parts.url = "github:hercules-ci/flake-parts";
    systems.url = "github:nix-systems/default";
  };

  outputs =
    inputs:
    inputs.flake-parts.lib.mkFlake { inherit inputs; } {
      systems = import inputs.systems;
      perSystem =
        {
          pkgs,
          system,
          ...
        }:
        {
          _module.args.pkgs = import inputs.nixpkgs {
            inherit system;
            config = {
              allowUnfree = true;
            };
          };

          devShells.default = pkgs.mkShell {
            nativeBuildInputs = with pkgs; [
              nodejs_22
              pnpm

              (python3.withPackages (p: [
                p.psycopg2-binary
                p.psycopg2
              ]))
              uv

              stripe-cli
              ngrok
            ];
          };
        };
    };
}

If there is no other workload, could I get an eval on gcc 14 to 15 update vcunat ?

https://github.com/NixOS/nixpkgs/pull/440456

Just rebased on top of staging-next to know if there are some major breakages I should address before marking as ready (would still wait for branch-off / breaking changes being unrestricted on staging)