The WGSL are generated and compiled through TVM and embedded into the wasm.

I think what you mean is wgpu native support. At the moment the web gpu runtime dispatches to the js webgpu environment. Once TVM runtime comes with wgpu native support (like the current ones in vulkan or metal), then it is possible to leverage any wgpu native runtime like what Zig provide.

Additionally, currently tvm natively support targets like vulkan, metal directly which allows targeting these other platforms

OK that makes sense; so basically if I want to give this a shot then I would just need to read llm_chat.js and the TVM docs, and translate llvm_chat.js to my language of choice effectively?

I think instead what would be needed is a wgpu native runtime support for TVM. Like the implementations in tvm vulkan, then it will be naturally link to any runtime that provides webgpu.h

Then yah the llm_chat.js would be high-level logic that targets the tvm runtime, and can be implemented in any language that tvm runtime support(that includes, js, java, c++ rust etc).

Support webgpu native is an interesting direction. Feel free to open a thread in tvm discuss forum and perhaps there would be fun things to collaborate in OSS

How big is the "runtime" part? My use case would basically be: run this in a native app that links against webgpu (wgpu or dawn). Is there a reference implementation for this runtime that one could study?

tvm runtime is pretty decent(~700k-2M level depending on dependency included), you can checkout tvm community and bring up the question there, i think there might be some common interest. There are impl of runtime for vulkan, metal that can be used as reference.