Interoperability: I believe we can do interoperability by selectively wrapping the necessary imports in 'unsafe'. From there, it's up to the implementer to decide whether to handle it as a 'Result' or an 'Option'.

Browser, Std lib: Yes, the language should still be able to run in the browser and will provide a std but will not transfer each time, the benefit of writing a compiler would be that we can do dead-code-elimination and target native javascript methods instead of something like wasm.

Lifetimes: Honestly, currently I'm only working on the simplest transpiler but I would like to explore using typed arrays as the stack, heap.