Libraries like `ethers` or `viem` work in React Native (with a few polyfills for crypto primitives) to build, sign and broadcast transactions from a locally-held private key or a hardware-backed signer.
import { ethers } from "ethers";
async function sendEth(privateKey: string, to: string, amountEth: string, provider: ethers.Provider) {
const wallet = new ethers.Wallet(privateKey, provider);
const tx = await wallet.sendTransaction({ to, value: ethers.parseEther(amountEth) });
return tx.hash;
}React Native lacks some Node built-ins (like `crypto`), so projects typically add `react-native-get-random-values` and other polyfills before importing these libraries.