Option A: Integrate a payment processor like Coinbase Commerce. Set up an account, embed their checkout widget, handle their SDK. Pay $100 in fees (1%).
Option B: Build your own blockchain listener. Learn ethers.js, subscribe to USDC transfer events, handle reorgs, confirmations, edge cases. Two weeks of work, minimum.
There's no middle ground. No service that just tells you: "Yes, this specific payment arrived."
Until now.