I made two posts on [email protected], neither are visible on both instances lemmy.ml are recommending.
beehaw.org has already become a much bigger instance and they ban lemmygrad, we’re already invisible to half the people using lemmy.
It will keep getting worse, at some point you’ll need to maintain two separate instance accounts and you’ll consider dropping one of them.
If two instances aren’t federated, users of each can’t interact with eachother. As to Hexbear’s federation plans, from a bit of lurking it seems which instances they will federate with - if they do so at all - is up in the air.