"Dutchia" is just Mio being dumb; the bit about the Netherlands is narration, not Mio talking.
It's worth remembering on this stuff that the Netherlands was the first nation to legalize same-sex marriage, in 2001; that fact was big enough news internationally that it was pretty much standard for lesbian characters in early-2000s comedy anime to have "emigrate to the Netherlands" as their stated life goal. Obviously this doujin postdates that somewhat (it was published in 2014), but the memetic value of the Netherlands in a yuri book was such that it probably wouldn't have needed the narration.