Upgrading unity version nightmare

So I have a project that uses Firebase that is 2019.4.5f1 and it works fine. I'm trying to upgrade my unity version to 2020.3.20f1 and it is a real trainwreck with about 65 conflicts between package files and same named stuff in the assets folder. Is there a guide somewhere on how to upgrade a unity project that uses Firebase. All the ones I found tell you how to install Firebase, but upgrading a unity project seems to be extremely complex.

forgot to mention the project also uses admob with Unity ads in mediation