Fediverse features for mutual aid/community organizing

I feel that decentralized social networks can help to realize some important functions for communities with regard to mutual aid and community building, but I do not see much action happening on that front, or at least I have not heard about them.

Specifically I would like to discuss how we can build mutual aid networks on the fediverse. What sorts of interactions or platforms would be needed to make this a reality?

Feature 1: Classified ads - “I need” or “I have” identifiers on posts allowing users to provide or request resources or services from other people

Possible existing platform - Flohmarkt

Feature 2: Events - Time, Date, Place, Location, allowing users to organize events, such as food not bombs, demonstrations, etc

Possible existing platforms - Mobilizon

Feature 3: Private groups - Invite only groups that allow for private discussion, classified and event postings, allowing users to organize in a private and secure way, without having to rely on a public forum like the current fediverse is.

Possible existing platforms - Bonfire

What does everyone think about these features for building mutual aid and real community building on the fediverse, what other features can you think of that would be useful for this, and what platforms/initiatives exist already to implement these features?