It's like Lemmy, but it can interact with Mastodon and has some other features that Lemmy lacks. It's pretty cool, only reason I don't use more often it is I'm happy on my instance otherwise I would swap in an instant.
It's not one company, but the top 5 companies make up 40% of South Korea's economy, with the top 30 76.9% of their GDP. It's scary to imagine the power they wield over the peoples lives.