The solution is to not treat communities like official and unique subreddits.
On Reddit there’s the PCGaming subreddit. On Lemmy there are more than five. Subscribe to all, or the most active ones, or the ones you align yourself better with… And that’s it, there’s no need to be concerned about which individual post goes on which individual community for a topic, it will federate and others will read it just fine.
That happens on Reddit even with singular communities. Sure, maybe some topics will come up multiple times.
Browse the All feed. See a post you like? Check the community. Not subscribed? Subscribe. Simple.