I’d need to read through their docs to sift how they do their alleged decentralization. But if those sites work as portals where you create an account and use through there, then I don’t think they’d be much different from ActivityPub.

Now, if there’s a way for you to have a site-less instance (IP, hash or signature-based, maybe?), then I could see how it becomes more decentralized. Or if they’d do, from what I could understand, as PieFed, where you can apparently change ownership of communities across instances, which despite not being as decentralized as the previous proposal as I understand, it would still be more than it usually is in ActivityPub.