A couple of places for motivated people to start:

https://civileats.com/2022/08/01/22-solutions-focused-stories-on-the-food-system-in-2022/

https://www.localharvest.org

https://www.opensourceecology.org

https://slowmoney.org/

https://www.indiehackers.com/post/12-community-building-tools-for-all-your-needs-1ffd8a88d9

https://mashtips.com/best-neighborhood-apps/

(NextDoor is listed here).