I don’t know of any community cell carriers, but co-op ISPs are a thing. Toronto Freenet was probably the first ISP I ever used (stretching the term a bit, since it was more of a BBS service at the time if I remember correctly), and it looks like it’s still going relatively strong.

http://www.torfree.net/about-freenets.html

Now there’s a name I haven’t heard in a while. I sank way too many hours into this (started off as a TA clone but branched off into other game modes too) a decade or two ago, and it looks like it’s still going.

https://springrts.com/