A community limited to your GitHub sponsors or a specific group of people

[egoist]

GitHub sponsors has a built-in Email Updates feature that allows you to email your sponsors at once, but you may also need a community like Discourse but only allows your sponsors to access. http://spectrum.chat has the potential to become a platform like this.

Another use case is providing service for your open source software, creating a community that only allows "paid users" to access, can be done with some sort of integration with Gumroad/Stripe/Paddle.