Facebook is one of the worst places to build a community. You now have to pay to post more than two links a month, even.

And you might be impressed how far forums have come. Open source Discourse forum now has built-in Discord like voice and video chat, along with real time text posts. (It also powers some extremely large communities with millions of users.)

Oh I agree in general, I don't have FB. And discourse forum is probably what I would have tried too, but can it really scale to millions of active users? The largest I know are some linux forums, but they are way smaller.