Online tools for organizing locally?

cross-posted from: https://hexbear.net/post/3876283

I'm passing this question along, because I think we might have folks here who have some suggestions.

What tools or combination of tools are folks using to organize in your local area and beyond?

A relative of mine was asking me about software to replace the event/RSVP/page aspects of Facebook.

It almost sounds like he wants a locked down Lemmy instance or a combination of tools, but I'm not sure what the landscape is like out there.

Any input would be cool. I might link him to this post later if I get enough comments.