How to know whether a *page* in an app is using React Native (or pure native)?

Note: I am not asking how to detect if an app uses React Native somewhere inside it (already has an answer here).

I wonder which pages (screens) inside an app is using RN and which pages are not, by examining the apk file or runtime checks etc. For instance, the Facebook app uses RN. However, it only uses RN for some seldom-used pages - that is completely a different story than using in every page.

Thanks for any ideas!