I have a shower thought earlier about this: what if there was a feature exclusive to community mods that allows communities similar to theirs to form a group?

Now what would the group do? Communities that are members of those groups basically would share data with each other and sync posts between each other. Community mods could send invites to similar communities on other instances to form a group. Say for example, technology@beehaw.org and technology@lemny.ml are in one group. Now if I post in Beehaw's technology community, it would also appear in Lemmy.ml's technology community because they are in the same group (probably with a flair-like feature that would indicate the instance from where the post comes from). Upvotes and comments will also be synced between the communities as well.

Now, what about moderation? The community mods in the respective instances still have power over what the community sees and if it obeys the community rules. Community mods could filter what posts would appear in their community's version. So if, for example, a person from lemmy.ml's technology community were to post something that goes against beehaw's tech community rules, the mods from Beehaw can block that post from appearing in the Beehaw tech community. It would not affect the Lemmy.ml community though. In this way, it preserves the decentralization of the fediverse while at the same time, making it intuitive for users too because they don't have to switch between similar communities because they can stay on their instances and still get content from the other instances with similar topics.