Which project would be best for a local community hub?

Mastadon? Lemmy? It would probably have to be standalone so people would't be turned off from the content from the rest of the fediverse unless there's a way to prevent federated content from showing on the instance. Just a place to post local news and discussions, maybe a place to sell secondhand. I live near a huge college with a major cs program, so I should be able to get users.