Sure. It's good security practice to keep firebase credentials and any other privileged information OUT of your git repo. (Less important if it's a private repo, but it could become public some day...)
Honestly, it doesn't matter too much if you email me the firebase config information, since I probably won't run your code for your individual projects.
I want to see you run your code, in your app demo, and I plan to read your code (up on GitHub), but I don't necessarily need to build/run it myself.
It might be nice if you could share your Firebase console for your project with me though, so I can take a look at how you structured your database. Open up the Firebase web console, and the specific project, and choose "users & permissions", and add my email address as a "Viewer" role.