Established G+ Exodus Communities
As of 13 October 2018, pluspora.com - increased membership from perhaps 100 before the G+ termination announcement (October 9?) to 5500 within a few days.
The MeWe community "Google Plus Refugees" has 124 members. "Google+" has 20 members. "Google Plus Expats" has 668 members. "Google Remnants" has 357 members. There are several other Google+ named groups in the 10 - 50 member size range, and there are various Google-related groups in languages other than English. As MeWe is group focused, some communities from Google+ may not have Google in their name at all and be indistinguishable.
The Cake interest category "Google" has 189 followers. Recent posts address the demise of G+. The category also tracks other Google-related matters including related consumer devices and working at Google, and others.