True in spirit but not to the letter. You can fire up your own server and federate Bluesky. The issue is that Bluesky’s centralized design means that you would be hosting a clone of literally all the data, which requires serious infrastructure and expense. But the protocol is open, so in theory an alternative provider (with resources) could do it.

If all Xitter users decamped to Bluesky, that might create incentives for more providers to step in, creating some competition and accountability. Non-profit foundations with deep pockets could do it, for example. That would definitely be an improvement compared to today’s corporate social media.

But I agree that ActivityPub is the more democratic solution.