I don't know about your nextdoor, but my nextdoor is complete trash. Half the posts are people asking for trades people recommendations and the other half are "this [minority] person walked by my house twice, anyone know if they're a criminal?"
Community building on that platform seems like it'd be really difficult with it's current atmosphere.
Oh, it's the pettiest platform. I used to like going on there and imperiously reminding everyone that we're all neighbours when things got heated.