I live in a small community that relies on Facebook, and I would be shocked if you could get people to switch. You might get a few, but the network effect is strong enough that most will stay on Facebook.

One alternative is an old-school email list. We have one run by a single older woman, who refuses any form of updates or help. If she’s sick, emails don’t go out. If you want to sign up, you need to ask her. Still, it’s easy for people to use on a variety of platforms, uses minimal data, doesn’t have any tracking, and doesn’t have ads. The longer-form, slower nature of email makes it less likely to devolve into drama like the local Facebook groups do.

Even if you do self-host something decentralized, you need it to be reliable without you. If you succeed and your community relies on it, you’re doing them a disservice by not making it a reliable even if your circumstances change.