Did you actually look at the link I sent you? It's absolutely not low level. If you know how to use window.fetch, you know how to use AbortController already.
controller = new AbortController();
const signal = controller.signal;
fetch("http://example.com", { signal: signal })
// abort request
controller.abort();
It basically couldn't be simpler? What sort of API would you like to be able to cancel requests?
That's a toy example! In reality in a complex app you'd usually be aborting far from where the fetch is created, and you'd have large promise chains where the semantics of cancellation are non-obvious and even unintuitive.