I have posted some updates on our issues getting ExpoKit apps to work on iOS 13 here Anybody else have problems with iOS 13 using the ExpoKit instructions? (UPDATE: not fixed) and submitted an issue here https://github.com/expo/expo/issues/5532.
I just wanted to cross-post here because we just confirmed we get a similar-looking (can’t see actual errors b/c it’s prod) crash on our managed workflow app. Looking at Expo’s RN forks, while they do have. the “__unused signature changed” error fixed, the fishhook.c fix (https://github.com/facebook/react-native/issues/25182) does not appear to have been cherry-picked. We are only seeing this issue on an iOS 13 beta device (in our case, an iPad mini 5th gen), and are not seeing it on any iOS simulators.