Here is how you make a hack proof wallet with current tech: Android: TEE wallet query interface with lockout or timeout, IOS: TEE wallet query interface with lockout or timeout, Intel x86: SGX, AMD x86: TEE wallet query interface with lockout or timeout. AES or EC signing on all. Don't have memory corruption(hand written assembly since it's so small)

Future vulnerability: Bypassing signing in isolation loader with silicon manipulation. This is what game consoles and Apple do and except where they have memory corruption it doesn't get hacked.