Add Nix support

.envrc

@@ -0,0 +1,8 @@
+#!/bin/bash
+
+# This is a better (faster) alternative to the built-in Nix support
+if ! has nix_direnv_version || ! nix_direnv_version 3.0.4; then
+  source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/3.0.4/direnvrc" "sha256-DzlYZ33mWF/Gs8DDeyjr8mnVmQGx7ASYqA5WlxwvBG4="
+fi
+
+use flake

flake.nix

@@ -0,0 +1,41 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.11";
+    flake-utils.url = "github:numtide/flake-utils";
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs = {
+        nixpkgs.follows = "nixpkgs";
+      };
+    };
+  };
+  outputs =
+    {
+      self,
+      nixpkgs,
+      flake-utils,
+      rust-overlay,
+    }:
+    flake-utils.lib.eachDefaultSystem (
+      system:
+      let
+        overlays = [ (import rust-overlay) ];
+        pkgs = import nixpkgs {
+          inherit system overlays;
+        };
+      in
+      with pkgs;
+      {
+        devShells.default = mkShell {
+          buildInputs = [
+            picotool
+            (rust-bin.stable.latest.default.override {
+              targets = [
+                "thumbv6m-none-eabi"
+              ];
+            })
+          ];
+        };
+      }
+    );
+}