Hi there,
I read your project requirement that you need a flutter app for the existing Project. I can build you a flutter app with all the features that you mention{ bluetooth nfc reader and retrieves Tag IDs, create an initial screen with email/pass login and screen for linking ID to text provided from user. When tag scanned, post to server} according to your requirement.
I have been a Senior Mobile App Developer for the last 7 years. I am confident I will provide you with a great quality of work meeting your expectations. I have rich experience in Mobile development and technology Android, IOS, Objective-C, Xcode, iPhone, iPad, React- Native, Flutter, Swift, Phonegap, Objective-C, Building Web APIs.
If you need to discuss with me for any kind of suggestion or information please knock me anytime. I am looking forward to hearing from you very soon.
Regards!!