It's unclear to me why they needed to compile Rust to WebAssembly to write a website. It looks like iroh has a JavaScript API:
https://docs.iroh.computer/languages/javascript
Edit: actually, that's a Node.js-specific API. For browsers, it seems like they should have a platform-independent JavaScript/TypeScript API that includes a WebAssembly file (if needed) instead of expecting you to compile WebAssembly yourself.
This is interesting as an example of just how complicated and elaborate a toolchain you can use to build something dead simple.
There’s a lot that comes for free by adding all these libraries and crates and steps. But from what I can tell it comes down to:
let _ = if fan_on { fan.set_high() } else { fan.set_low() };