A company called Taalas is working on something like that. Not Opus4.6 quality, but I'm sure they're targeting larger models. Currently they're using a LLama 8B model. It runs at ~17k tokens per second, and you can test it at https://chatjimmy.ai/.
I’m not sure if this is what you meant, but at 17k t/s, you start to compete with the speed of network calls. You could approach the point of generating an HTML/js/css page faster than some websites can be returned over the network.