My hobby group has zero income as well, but we passed the donation hat around and got about 15% of our membership to throw in a couple of bucks each.  They were thrilled to express their appreciation with small donations.  With one donation drive, we actually raised enough for 2 1/2 year of premium membership.  If a membership values the group, there will likely be sufficient donations to cover nominal costs, but leadership needs to make the effort to make something like that happen.  It really doesn't take that much effort to accomplish.  Nonprofits at G-Suite/Workspace may not pay membership costs, but someone is paying for the services and storage. . . whether its from ad space revenue or collections from other paying groups.  In the end, free services tend to go away. . . user beware.

My group really appreciated being able to save our 10+ year history at Yahoo Groups by transitioning to GIO and then utilizing the unique features provided here with GIO premium.  The capacity for storage organization is a HUGE plus for us.  But as you remarked, each group is unique with different needs.  I don't believe Mark is looking for number of groups, but those who want to support his work in building GIO up further.  He certainly provides developer access and input unlike anywhere else and has developed quite a loyal following because of it. 

RCardona