This site is currently struggling to handle the amount of new users. I have already upgraded the server, but it will go down regardless if half of Reddit tries to join.
However Lemmy is federated software, meaning you can interact seamlessly with communities on other instances like beehaw.org or lemmy.one. The documentation explains in more detail how this works. Use the instance list to find one where you can register. Then use the Community Browser to find interesting communities. Paste the community url into the search field to follow it.
You can help other Reddit refugees by inviting them to the same Lemmy instance where you joined. This way we can spread the load across many different servers. And users with similar interests will end up together on the same instances. Others on the same instance can also automatically see posts from all the communities that you follow.
Edit: If you moderate a large subreddit, do not link your users directly to lemmy.ml in your announcements. That way the server will only go down sooner.
So the problem with beehaw is... It's nice and has queer people on it? And banned one other instance.
The issue with lemmygrad as I understand it is that they have a lot of "tankies", aka specifically the type of "communists" who support nominally communist dictatorships, such as supporting China against Hong Kong, Russia against Ukraine, etc, and denying historical war crimes commited by Stalin and Mao and so on. This isn't popular with other communists and socialists because it's less communism and more blindly eating dictatorship PR.
However admittedly I am on beehaw and would have to go out of my way to actually look at lemmygrad much myself, which I have not done.