It doesn't have browser support yet because it's WASI-based, so there are a few more steps compared to Emscripten (two different ways to build for WebAssembly). But networking is supposed to work, did you have trouble with it?
With RISC‑V emulation we get the virtual hardware components we need to boot Linux like MMU, registers etc. So a GCC WASM backend could definitely help, but I'm not sure it could replace the whole emulation layer.
The worst that could happen is having your credentials stolen. It’s an LLM architectural flaw, so it has to be at the tools level so the only way to prevent it is still sandboxing in my opinion. Or at least sandboxing the tools themselves
You can avoid the serialization in WASM by pushing structured bytes to the SharedArrayBuffer, then do serialization in JS which should be relatively cheap compared to pushing JSON strings across the boundary.