The easiest option ATM would be for an app to combine both communities into one synthetic feed

In a perfect world I'd like to see some kind of meta community system where the individual communities still exist but kind of automagically cross pollinate with each other so that users, server, and moderation load is split somewhat democratically. Not going to happen any time soon since it would probably take dev work and they have their hands full.

Practically what will probably happen is certain communities will become the "standard" ones and others will be smaller versions, just like there were countless "true" subreddits.

What you can do is subscribe and post to whatever one you like, and then feel free to cross post to other communities. Cross posting works really well on Lemmy.