The dev's stated milestone for 1.0 was "all 20 reigns in the game", which has technically been completed, although I agree that he should have finished their routes, first. He at least shouldn't have left Mermaid and Finhead dangling like they are now.
I remember that, but that was kinda the arbitrary change I was talking about. Unless I'm tripping (this game's been in dev for so damn long...), the stated 'completion' of the game was originally all routes, because that is the fing point of a run outside of exception side runs. He also mentioned (and does at least talk about it in the steam announcement) that it was long overdue and it didn't make sense being in EA anymore, which I'm pretty sure is also why the 20 reigns was arbitrarily decided to be the new goal.
Either way, the game still isn't finished as the reigns are all over the place in terms of completion and some barely have any of their routes done so are kinda just...there.
And by this definition, the game might as well been considered complete 5 years ago because he still plans on adding more reigns in the future and current ones aren't even finished, doubling down on just how arbitrary that new target was.
But anyone coming in hoping to play a complete game with all gameplay loops and narratives finished isn't going to find that. I in no way would consider that complete. For the record, I bought the game on steam years ago, and as a fan, I still think calling the game complete is at best an ironic joke.