If you’re poking around WASM consider falling down the Component Model rabbit hole:

https://github.com/WebAssembly/component-model/blob/main/des...

Threading is actively being worked on right now (to be released in 0.3.x, soon), and some changes just made their way into LLVM as well:

https://github.com/llvm/llvm-project/pull/175800

Iirc the async stuff in the component model isn’t actual threads but rather green threads, but correct me if I’m wrong