Open-source tool for communities/groups to help each other during Corona

Looking for recommendations for an opensource tool that could easily/quickly be setup and configured to support individuals that belong to small groups/communities to share information and communicate with each other.

E.g. a neighborhood where someone who is isolated due to Corona virus and sign-up and request supplies/assistance. And where interested people can post offers/information (with moderators).

Self hosted so that privacy is maintained (i.e. not Facebook). Preferably on a low-cost service like DO or Heroku.