Maybe I'm misunderstanding some aspect here, but it seems to me there are two choices for handling external data in TypeScript:

Either you parse / validate incoming data at an API boundary with a tool like zod, or you do not, and just trust that the data matches the exact shape you expect, opening yourself up to completely unexpected errors / behaviors if it does not.

The latter is probably a decent option if you fully control all components back to front, but if you really value type safety, the former seems like the way to go?