index.js

import { generateKeyPair, exportJWK } from "jose";

(async () => {
  const { publicKey, privateKey } = await generateKeyPair("EdDSA", {
    extractable: true, // 👈 this is the key fix
  });

  const pubKey = await exportJWK(publicKey);
  const priKey = await exportJWK(privateKey);

  console.log("ed25519-pub.json", JSON.stringify(pubKey));
  console.log("ed25519-priv.json", JSON.stringify(priKey));
})();

package.json

{
  "name": "create-ed25519-jwk-with-npx",
  "version": "1.0.0",
  "bin": "./index.js",
  "type": "module",
  "dependencies": {
    "jose": "^6.0.12"
  }
}