The simplest possible x402 transaction. One sender, one recipient, devnet USDC.
What this is: The x402 primitive stripped to its essence. One HTML file and a wallet. The page builds a USDC transfer, your wallet signs it, and the page sends it straight to Solana's public devnet endpoint. That is the entire payment stack.
Devnet only: test tokens with no value. Switch your wallet to Solana devnet, then get devnet SOL from the Solana faucet and devnet USDC from Circle's faucet.