I'm quite sure as soon as there are performant WASM engines deployable outside a browser (e.g. parity-wasm) then Ballista will converge on it and it would hence

I'm quite sure as soon as there are performant WASM engines deployable outside a browser (e.g. parity-wasm) then Ballista will converge on it and it would hence support anything that can compile to wasm. In fact, I think the time to begin that type of project is now because by the time you do the ground work for such a project and integrate, etc. a wasm engine will be ready.