But I want them to make TS fully sound, which they say they’re not currently doing. Maybe one day?
There has been attempts in the past (https://hegel.js.org) but I think TypeScript has been successful because it is prioritizing DX and ergonomics.
In the age of LLMs, the compiler can be a lot more strict. JSON.parse should not return `any` just to make developer happy and keep moving. It should be `unknown` and force the developer (LLM really) to do the hard work of writing down the type of what that JSON _could_ return. This is the philosophy of the Sound Mode in tsz. You'll get closer to Hegel ideals without making it impossible to write code and/or promising absolute soundness that JavaScript simply can't support.