The primary motivation was to learn both WebAssembly _and_ a new language. However it turned out to be a very fun project, and I think there is space for a decoder with helpful error messages, that can serve as a good debugging tool or for educational purposes.
A sample output can be found at for an invalid module can be found at https://github.com/agis/wadec?tab=readme-ov-file#usage.
Recently it hit v2.0 spec conformance (I'm executing it against the upstream spec test suite.) 3.0 is next on the roadmap.
It's still in very early stage, but any feedback is more than welcome. Thanks!