Best online communities for people building the future?

Looking for recommendations on the best places online to co-work and interact with others who are focused on the hard unsexy work involved in going from zero to one.

Ideally places where technical folks gather to bond, exchange ideas, and work together.

Imagine an online version of NYC's Recurse Center or YC startup school -- high caliber people working hard toward achieving difficult things.

Any discord / slack / websites / other groups where smart people are hanging out and working on stuff?