This works the same as Expo Go. You run npx expo start and open the dev build on your emulator or phone.
You only need to build again if you install a new dependency.
If you were using Expo Go before then you might not have the push notifications set up properly. Expo Go of course has its own android.package value, which is different from your app. I have not looked at notifications in a long time, so maybe read through the troubleshooting documentation and make sure you have everything set up correctly.
If you have run npx expo prebuild or npx expo run:android then you basically have a Bare workflow app. In a Bare app you need to do some extra stuff, I believe, so I suggest you delete the android directory, read through the troubleshooting docs and create a new development build with eas build --profile development and hopefully that will get it working correctly.
EDIT: This part of the troubleshooting guide might be relevant: