I think the conventional way this is handled on Reddit is separating memes and fluff into one one community (subreddit) and more discussion based content into another community. It works on Reddit because even if the memes get more engagement in an absolute sense, each subreddit has it’s own yard stick for what is doing well, so a discussion that makes it to the front page of its own subreddit will make it through to the front page of users who are subscribed, alongside the memes. I don’t yet know enough about how Lemmy ranks posts to know if this will work, but hopefully it will.