Mobile App Revamp & Barcode Tech Integration

I need someone to help me revamp my existing mobile app which i vibe-coded, i think the design is fine but if it's not you can suggest a better design approach. Make sure you test every aspect of the app and it's behaviour, to be honest i don't really understand the mechanics, but i need to connect it to a backend maybe firebase or supabase whichever you think it's fine. I have a warehouse and packages comes in bulk with bar codes attached so i want the app to be able to scan multiple bar codes as fast and possible, extract the texts and store them and present them in a way every other warehouse can easily reference the information. useful for stocking, transit, delivery etc. the app is currently android and i haven't tested it on an ios yet because i don't know how to go about it, if you can make it perfect first on android before working on ios no problem and if you can do both i will appreciate. kindly download it, review it and send me your budget and quote as long as it doesn't exceed 3500 to 4500 range.

https://drive.google.com/file/d/1tfEzc2o4e9HozCFoGZ-yeCdbYznDaaOj/view?usp=sharing