How to extract fetch headers without awaiting a request in the browser console?

I am working in an application that uses a headless web browser, DrissionPage. The details or code are not relevant for the question.

I need to extract all fetch headers (such as cookies, user agent and others). And it needs to be using the browser console (Chromium).

In DrissionPage, I can get the result of an expression, as long as it is synchronous.

It is also possible (but not best practice) using asynchronous code, I could always do a while loop and wait until the promise is available, or insert it into the DOM from a callback and then read from DOM using drission selectors. But I would rather have a way to do it synchronously.

This is because run_js returns Any (and it does indeed return the expression result).

But run_async_js returns None.

I can get the results of a synchronous JS operation this way:

print(tab.run_js('''
        (() => {
            return 1;
        })()
        ''', as_expr=True))

So my question is, how can I extract the headers that would be sent by a fetch call? Preferably without firing the request or any async code for that matter.