That's where it started, but they're entirely separate banners now.

It is actually not allowed to organize raids or other Anonymous-style hacktivities that are against US law on 4chan. So, calling for cyber war may just net you a warning from moderators. The board is not the bastion of absolute unregulated free speech people think it is!

More broadly, outside of the current geopolitical context, trying to pick a target and rally anons against it is in bad taste. If you try, you may be told that "4chan is Not Your Personal Army" (NYPA).

As a result, the various "Anonymous" groups really don't have a home there.

The "real" Anonymous was. Now some other hacktivist group uses the name to cash in on the clout. People get really excited when they hear Anonymous is back at work.

And even then it’s mostly a bunch of kids larping

That's all it ever was

4chan is so big these days, a mere board like /pol/ will have 30 million unique IP visits per month, that is (perhaps unfortunately) more than just kids these days. It's the main free speech board of the internet, it draws people from all over the world.

It’s nowhere near that big.

When I didn't know better I thought them as some kind anarcho libetarian group, but behind every effective cyber offensive there is always a powerful actor.. mostly a state or private interest.

Not necessarily 4chan, but yes. Its name can and has been claimed by different groups.