In the Sound Mode page I mentioned that I have some ideas around this. What if we could take .d.ts and project a sound version out of it? How feasible that can be is unclear but the biggest unsoundness criminal is `any` which is relatively safe to project it into `unknown`. And method binvariance stuff are also not impossible to project something more sound out of it.

My goal with tsz is to make it practical and useful. I know how difficult it is to convince a tsc user to try something not officially from Microsoft