I don’t really see it as an issue. Post it to whichever community you are most active on. If people want to part of that particular instance, they will see it and interact with it.
Just like I’m interacting with this post right now even though I’m not on lemmy.world. I’m quite over what became the gamification of karma on reddit, and really hope it doesn’t become a thing here. There’s no reason about having to worry about which instance to post something to, people will find it and interact with it.