@Andrew A's answer is actually correct.

The error I started getting [runtime not ready]: ReferenceError: Property 'document' doesn't exist, js engine: hermes was caused by React Native styled-components library. The older versions of this library try to reference the web document object, which is no longer available in the new architecture.

I had to do an extra step of upgrading styled-components to version 6.1.18 or superior, which supports Expo53. Also make sure I'm always importing "styled-components/native" instead of "styled-components".