I have an already published project on the App Store developed with React Native. We are migrating it to SwiftUI, and I need to upload the project as an update instead of creating a new one for this new development. How could we go about doing this?
I need to update an app developed with React Native to SwiftUI without creating a new app
Your bundle ID is what identifies the App Store Connect product that you'll upload the new version to, so make sure you use exactly the same bundle ID in your new project. By default, the app module name is that last component in the bundle ID, but in cases like this you should override the entire bundle ID with the exact bundle ID you want.
It's also worth mentioning that your team ID matters too. You probably haven't changed which developer account (and therefore which team) you're using, so you probably have nothing to worry about there. (However, if you used an old "random" app ID prefix instead of a team ID, you will need to use that in the new project, too.)
You should also be careful to make sure your new Xcode project capabilities match the ones that you previously used. You can expect upload errors if your capabilities don't match what App Store Connect thinks this app's capabilities should be.