Firebase, in the doc here
Document "A":
https://firebase.google.com/docs/unity/setup
it claims that it DOES now work for desktop builds. (So, in unity you create a Mac app or Windows app.)
it does work perfectly "in the Editor" (on Mac or PC), which is great
it does NOT seem to work as a Mac or PC build - I cannot get it to work
And here for instance..
Document "B":
https://firebase.google.com/support/release-notes/unity
.. it suggests it is not working (although its' a bit confusing).
Is it not working yet, or did we just screw up?
This is a bummer.
As I mention below, you can't use Firebase for VR until this is done, since VR builds are Windows builds.
firebaser here
While most Unity SDKs for Firebase should now work in the Unity editor, build targets for desktop environments are not yet supported. So: you can develop games targeting iOS and Android on the desktop, but you can't target desktop games yet.