because Google's stuff is so integrated into so many sites for many people - from analytics (which you have no choice of) to "Sign in with Google" (which you do), embedded Youtube videos, Gmail, Calendar, all the hosted libraries (jquery being the most popular), i just don't see a "google tab" are workable.
I've tried making my own. The problem is even though I use ProtonMail, and Etesync (calendar) and tresorit (storage) and signal (messaging) and Duckduckgo and stay on Firefox unless i have no choice, is that i still end up with lots of stuff running in the same tab that is "non-google" simply b/c everything utilizes and embeds so many google services.