But I do everything with Construct plugins, there isn't anything for firebase is there?
I thought that seeing as there is a Google Play plugin, functionality could be added to that.
It isn't as easy as that to add, for information's sake. And also, I inquired that with Ashley before and he said::
Construct 2 already has a savegame system, which uses browser storage. If you want your savegames to be synced to other devices, it doesn't seem like a good idea to pick platform-restricted services - presumably you'd want to cover all platforms. The API in the original post looks limited to Android only.
So, it is most likely they won't implement back-end services that are platform-restricted, as he said.
And I also asked to implement a cross-platform back-end service, which is Firebase. Which was denied, since there are a lot more prioritized features to implement.
But if you want to try, feel free.
There are Firebase Plugins for C3, but most of them are private though, since they are customized and doesn't cover all the features.