Truth Social is running Mastodon under the hood. But nobody considers it a part of the fediverse, because even if it had federation turned on it would instantly be defederated by 99% of instances.

I’m sure there are nazi lemmy instances out there, but they are all defederated from the lemmyverse. This is the correct approach, decentralized platforms are somehow doing a better job at this then the de-facto centralized bsky.