It is very disappointing there are no embeddable, performant wasm runtimes. The language is perfect for embedded systems, it's a near asm level sandbox. But there's no good no_std or limited dependency runtimes! If wasm is to grow, it should work on this use case.

I should be able to provide platform APIs to allocate memory, maybe do some floating point math, and then that's about it. Additional features would just be giving some additional API implementations the runtime needs to interact with the host machine.

Context: this was a huge barrier for me on my project https://github.com/mandiant/STrace/blob/16859a811e4af7c68259...

Have you looked at WebAssembly Micro Runtime (WAMR)?

https://github.com/bytecodealliance/wasm-micro-runtime