Luau itself does by design, but I've never tried compiling Lune to WASM. I know that there are some blockers with the Roblox library but that's an optional component and you can just leave it out.
The WASM build is actually what powers the demo on their website: https://luau.org/demo
Hey! Yet another long-term contributor to Lune, and this is something I've experimented with for a while, but it wasn't possible due to our heavy reliance on Tokio for async I/O for a while. That has recently changed though, so I'm curious if that has changed much. I might try again and report back here.
However, I should mention that there is another Luau runtime called cart which has the sole goal of being heavily portable across environments -- and it supports running within WASM! You can even interact with JS APIs and mutate the DOM to write websites with it, if you wanted to.
The WASM build is actually what powers the demo on their website: https://luau.org/demo