If you're not in the main instance, your going to be handicapped in your ability to stay in the loop. First because now everything goes through federation, which was a design afterthought for Lemmy, and that means stuff outside the instance always takes second place to what is inside the instance. Then you have issues like federation which are extra layers of censorship for everything outside your instance.
I've of the biggest problem is accessing outside communities. First you have to actually go to other instances and find them. They won't show up until at least one person subscribes. And this has to be fine in every instance for every other instance and every communities in each of their instances before they would even become visible. Of course, this is such a high bar that by the time you do all this, you'll realize 99.99% of users will not go through this trouble. They will just go to the biggest community on the biggest instance.
Last problem, if you go to your instance/c/acommunity , you'll see only that instance's "acommunity"
There is no way to refer to "acommunity" for the entire fediverse. There is no fediverse community. Only parallel, same named but unrelated communities that would require extra steps to view all at once if it were even possible.
There is a proposal , an old proposal, to create multireddit like feature for Lemmy. But first, the devs so not want to test down this barrier, si they won't do it. But even if they did, it would not work. Since you'd have to take extra action to aglomerate selected communities with a multireddit, you would be one of very few people to do so because agglomeration would still not be the default. And that means most communities would remain empty deserts anyway.