As an experienced React Native developer, I have an in-depth understanding of your needs and the challenges that come with integrating Google Sign-In functionality into a React Native Expo app for both iOS and Android platforms. I've had hands-on experience with the exact issue you're facing, as I myself have dealt with error 400 and found solutions without downgrading React Native versions. This means, even amidst potential obstacles or bugs, I can ensure your project moves full steam ahead.
Moreover, my knowledge stretches beyond just React Native. Having also worked extensively with Firebase, incorporating its user management system is a task I'm equipped to handle effortlessly. While my 8+ years' experience in graphic and web design showcases my ability to adapt to new technologies and environments, all to give your project a unique yet effective approach. Thus working on your project would be in sync with my skills and interests.
With over 620+ good reviews, my clients appreciate the dedication and efficiency I bring to each project. My mission has been to equip businesses through effective strategies and reliable branding, making me a reliable choice for this job too. Let's bring your vision of seamless google sign-ins to life!