I've also experimented with Go for both frontend and backend, using WASM. The approach I took was build the client-side like a backend service. What I mean is, some (normal) requests from the browser reach the hosted server, while others reach the local WASM. That code running locally is written like a server, i.e. HTTP handlers.

It's definitely experimental. In my experience it pairs well with HTMX or Unpoly for a good UI. You can see a live demo at https://clientcide.d10.dev/.