Yes, Wuffs can do better than WasmBoxC because it does more than sandboxing of the code. It also checks things like integer overflows which can lead to exploits that are technically not memory safety issues, but still potentially dangerous.

But the tradeoff is that you need to rewrite your code for Wuffs, while WasmBoxC can sandbox anything that compiles to wasm and prevent it from corrupting the outside, including existing code in C, C++, Zig, unsafe Rust, etc. etc.