Web3explainedby someone whorecently got it.

// User must have MetaMask installed
// User must buy gas tokens first
// User must switch networks manually
// Every tx shows a scary popup

const provider = new ethers.BrowserProvider(
  window.ethereum  // undefined on mobile!
);
const signer = await provider.getSigner();
// ↑ triggers MetaMask popup

await contract
  .connect(signer)
  .vote(proposalId);
// ↑ another popup
// ↑ user must wait 12–30 seconds
// ↑ if they don't have MATIC, it fails

// User logs in with Google — that's it.
// Embedded wallet created silently.
// Gas sponsored by your paymaster.
// Zero popups.

const { user } = usePrivy();
// ↑ Google auth → wallet auto-created

const userOp = await smartAccount
  .sendTransaction({
    to: contractAddress,
    data: encodeFunctionData({
      abi, functionName: 'vote',
      args: [proposalId]
    })
  });
// ↑ No MetaMask. No seed phrases.
// ↑ No gas tokens. Works on mobile.
// ↑ User never knows they have a wallet