Good point.

So many great exec environments already for WASM. Is there already something available for Unity? Maybe even with a source language and compiler built in?

My focus currently is on creating code inside a running app (by the user) with references to selected Unity objects and their methods. While WebXR is great for this, the first (and sometimes only) SDK implementations for certain devices are usually in Unity.

WASM probably ist great for hotloading but would need a more complex toolset available at runtime to edit and create. Interactivity and incremental code creation would also be better in a scripting envirnment.