sure, they are decentralized, but still, there's only one service. You can move to a different "server" but BlueSky is BlueSky....here there's Pixelfed, PeerTube, Misskey, Sharkey, etc.

You can't move your data between all of them, but there's a few you can like Mastodon/Pleroma/Sharkey

They have this protocol, but it's too new and I don't know if they're actually allowing devs to work with it yet for their own projects.