Gotcha!

Perhaps a stupid question, but as a new member what should I expect from de-federation? I completely understand and agree with the rationale for splitting off for now, but would this mean if I wanted to browse something on another instance, I'd need to make a separate Lemmy account?

That's a good way to put it. I'm still partially in denial and think it's possible for the admins to reverse course. But I admit, it isn't terribly likely. After the 30th I'm giving up on it.