Yeah. The client tool does make a difference. For example opencode, if I am correct, just spins up its own language servers and then feeds the language server errors back into the model, resulting in a much better agentic coding experience. I don't think they are doing anything much more complex than that.
Unfortunately, nearly all the foundation model companies are just wasting their efforts on the clients, which are kind of ass, instead of focusing on the model.
Google would be much better off if they ditch their dogshit cli, and allow us to have the generous quota login off any client.