As far as Juniper goes, people are claiming she’s non-binary due to the game’s code. They’re making a big deal about it, even though Juniper is kinda trash gameplay wise. Still an interesting character based on the cutscenes in the game.
Unfortunately, the guy who said that Shiver is female is Nate Bihldorff. People say he censors LGBTQ characters, like Vivian from Paper Mario: The Thousand Year Door, who is apparently male in the Japanese version, and then became female in the English version, making Vivian trans. Nate Bihldorff did not develope Splatoon 3, so we can’t really take his word for it.