Rather off-topic, but in case it’s helpful: my understanding is that Rust is compiled to LLVM IR, so in theory you could use my LLVM backend for Glulx to bypass going through WebAssembly and possibly generate more efficient code. I haven’t looked at it in years, and definitely don’t have time to maintain it, but feel free to grab any code from it if it’s helpful.
(Actually, taking a look at my local repo, I realize in 2022 I added an assembler so that the backend could produce .ulx files directly instead of Glulx assembly, but never pushed it – if that would be useful to people, I can try to clean it up.)