You still have to deal with the Android build system, `flutter new` just generates initial config for it and all the other necessary metadata (and that config can change between versions - I ended up manually diffing the generated stuff against a new app every time I upgraded).
At some point I made the mistake of not touching the code for too long and upgrading Android Studio when suggested, and I was never able to (find the time needed to) get that app working again.
Side note: Is anyone using Flutter just for Android? I'm kind of tempted to try this as dealing with the Android build system and packaging is bit of a pain, despite Kotlin and Compose being quite nice.