Can I add multiple Flutter apps to a single Firebase database using the same Firebase app?

If you have multiple Flutter apps (say one for regular users and one for power users) and make all of these available on multiple platforms, you will need to create app registrations for each of those in your Firebase project. So you'll end up with Flutter application count * platform count application registrations in your Firebase project.

Keep in mind that you should only put multiple apps in a single Firebase project if they are part of the same application suite. So apps for regular users and power users are a good example of this, but if you are an agency building apps for multiple customers, those should not be in the same project. I heard someone on my team explain this as "different logos should be in separate projects", which I also found easy to remember and apply.