This really should be a WebAssembly runtime so that the same computations can run on different platforms and devices.

We have Wasmer :)

https://wasmer.io/ (some cool examples here https://wasmer.sh/)

Wasmer is one of many WebAssembly runtimes, not sure why it needs specific hyping here.

I tend to use Wasmtime, V8, WAMR, and browsers. The point of WebAssembly is that there are many runtimes.