Do you think the steps from this: https://stackoverflow.com/questions/41896479/firebase-xcode-linker-command-error-using-firebase-unity-sdk?rq=2 Thread will help in my case? the guy that answered said something about the -ObjC flag and a couple other steps, but I dont use Unity Cloud Build, so I dont know if this will fix it

Errors happened because there was no .xcworkspace generated. I was able to solve this by following this amazing video on youtube: https://www.youtube.com/watch?v=CKvsG-_oIBM . After that, you will generate .xcworkspace file and not project one which will solve the errors.