I find Google Container to be an excellent plugin to segregate my Google account from the rest of my browsing. It's not an official plugin from Mozilla, but it is forked from the Facebook container plugin.
Same here - been using Google Container for 6+ months now and very happy with it. Highly recommended - you can do this yourself with just normal containers in Firefox, but this comes preconfigured with all the non-obvious domains you might not know about. No connection - just a satisfied user.
Only problem with it is now reCAPTCHA sites are a huge pain to use since you have to answer about 15 challenges before you can get (since you look totally unknown to Google outside of the container). It is often better to just ignore these sites now, but it is not always possible.
I just use Firefox containers. It puts every site into its own container. Then I made a "Google" container so that at least my login will hold across the various Google services.
Check into Containerise. You can setup wildcards and get the same effect with a lot more bad actors. Facebook properties are the worst in my opinion, with Google being a close second.
