FEAR NOT YOUNG ONE, BUT I SHALL TEACH YOU. For the Scoreboard, I have been a fan of them since my first game development class, where I did a vampire survivor game, I added a scoreboard, and i felt like this type of arcade game also needed it. So How exactly does this scoareboard work?
I used something called Talo. A free database to store user information. Really easy to set up too. All i did was grab my API key which allows me to access their database where I created 2 tables, a player and a high_score. When the player clicks enter on the enter name scene, I call the api to input the user, and the score, where i grab it via a global script so its accessible towards other scenes. Godot has support on it on their asset library, so when creating a project, you can add that addon. Im not sure if i can send links here but read their documentation and the creator also has videos!