The Fusaka upgrade has introduced EIP-7951, enabling smartphones equipped with Trusted Execution Environment (TEE) to function as Ethereum hardware wallets. This advancement allows these devices to sign Ethereum transactions using the secp256r1 curve, resolving a compatibility issue with modern security chips. By implementing a precompiled contract, Ethereum has reduced the gas cost for r1 signature verification to 6900 gas, down from hundreds of thousands, making it feasible for practical use. This development is a significant move towards 'account abstraction,' allowing users to authorize transactions through biometric authentication, eliminating the need for traditional hardware wallets.