@theaverageoni For what (little) it's worth, I gather you're doing it right by using the hashtag and following Black fediverse members.
Black servers tend to be targets for harassment so it takes more skill and resources to keep users safe. I know two which survived and seem to be doing well now, but they both went through crisis periods which turned many of their new users off Mastodon.
@theaverageoni far as I've been able to find the biggest one is blacktwitter.io, and then there's also terror.black. rage.love and mage.town are all pretty up front about centering Black voices.
Oh, and there is also my server! We're small but my users seem to like it here.
And if you're not picky about being on Mastodon only, there's also wibblur, which does have a larger membership than those I named but doesn't federate.