expo init testproj --template expo-template-blank-typescript
expo prebuild
xcodebuild -workspace testproj.xcworkspace -scheme testproj -configuration Release -allowProvisioningUpdates build
leads to:
/Users/reto/tmp/testproj/ios/Pods/Pods.xcodeproj: warning: The iOS deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0, but the range of supported deployment target versions is 9.0 to 14.5.99. (in target 'boost-for-react-native' from project 'Pods')