I’m looking for something where I can do some local community building, I’m guessing mastodon might work but I think the ideal is something like facebook where I can join a group tied to a common idea and a location, as well as being a bit more personal. Is there anything like that?
Getting a critical mass of people to sign up for the service depends on having something to offer those people. In the case of Facebook, that offering was initially “this is where you can find your hot classmates” and subsequently “this is where the hot college students hang out”.