From skeptic to convert: how Fieldy adopted Expo for their AI wearable

Fieldy, an AI wearable startup, shares their experience migrating a performance-sensitive React Native app to Expo. Key wins include a 25% app size reduction by removing redundant packages (react-native-calendars, lodash), fixing tree shaking, and deleting bundled system fonts. They adopted Expo SDK 54's WinterCG-compliant fetch to replace proprietary BLE and file upload libraries, wrote their entire BLE layer in native Swift/Kotlin via Expo Modules, and automated CI/CD with EAS Workflows including fingerprint-based OTA updates. A notable mistake: accidentally pushing a development config to production via a local deploy, which took down their paywall. Continuous Native Generation (CNG) simplified native layer management and a Gradle config plugin cut build times by 40%.