1 - Find out the database table template here. Duplicate it and add your lyrics.
2 - Download it in CSV
3 - Create a new SQLite database named lyrics.db with SQLiteStudio and Import the CSV file
4 - Overwrite the .db file inside the assets folder
When you update the lyrics.db file don't forget to clear the device storage otherwise it won't update the lyrics but use the previous one instead.
Then you can run the app.
flutter pub get
To rename the app, change the name of the app in AndroidManifest.xml for android
Change the icon in assets/icon.png and run
flutter pub run flutter_launcher_icons:main
If you happen to want to change the lyrics.db file name, you need to change it in the database_helper.dart and the pubspec.yaml file.
To use the list as a homepage instead of the numers just change the home widget from NumbersGridScreen to SongListScreen.
You might also want to change the appbar titles for the NumbersGridScreen and the SongListScreen.