I found fishing for (and following) hashtags on Mastodon effective but Mastodon was also in much better shape to receive the waves of Twitter exoduses.
Lemmy lacks effective tools to organize a feed. I think many people recreated their favorite subreddits as communities but the userbase was too small to support them. Being able to create “multi-reddits” to group related micro-communities together to help mitigate the ghost town feeling as you raise the probably of at least one of them having something new to talk about.