The title "Javascript to Rust and Back Again" had me believing that this would be a tale of how Rust was abandoned in favor of Javascript! I'm so glad to see we're actually talking about wasm interop
At our local Rust meetup we have someone who's gotten WASM running on a microcontroller, so maybe that's not entirely unrealisitic. :P
Wait, who was that?
This is somewhat related, although embedded here means embedding interpreted WASM into a CLI application.
Similar method might be doable on an MCU.
https://fosdem.org/2018/schedule/event/rust_embedding_wasm/
Then there's "WebAssembly interpreter in C":
Looks like it might be good enough for implementing WASM "scripting" support in smallish environments.