PieFed's categories of communities / Topic areas does this. When I used Lemmy I never found anything remotely close to that, but perhaps the best was to (1) visit each and every community that you want to check up on individually, and/or (2) use New rather than Hot or Top... and then be prepared to block hundreds of communities that you never want to see content from, like sports or individual locations (cities, towns, stateships, regions, countries, etc.).

PieFed also combines all comments across all cross-posts, reversing the fragmentation effect from having too many communities split across many instances.

You all on Lemmy need to catch up!:-P