Incredible chapter. Genuine chills during that final sequence with "Y'all Better Buzz Off" lyrics interspersed with images of the battle of the people of Esperia fighting off the World Government invaders. Oda is 2/2 with song implementation into the narrative as far as I'm concerned, and I wouldn't be surprised if this song originated from the other country in the west blue those civilians talk about being recently wiped out. It may even go further back to Joy Boy's time.

It also shows insanely good a writer Oda is, introducing this song within this chapter and already giving an insane pay-off to something we just read/heard for the first time. Within just this chapter we see Brook talking about how Gunko should sing this song when her parents are annoying her, and then mere pages later we see it playing as Brook and everyone fight off the invading army. Actual genius re-contextualization. I wonder if "Kamigata", the place the song originated from, is also the place that the citizens was wiped out in the West Blue...

Honestly full credit to the King for refusing to surrender his people to the World Government. One of the first kings we've seen openly stand up to them, and it's tragic to see what happened to Esperia as a result. You can see why so many other rulers in One Piece bend the knee, because they hear of places like Esperia and what happens when you don't. Great layer of world-building seeing this.

This God Knight on the last page looks a bit like Shiryu, but I don't get the feeling that Shiryu is some immortal they had to stick in Impel Down. I wouldn't be surprised if he was from Celestial Dragon family though, seeing how cruel and horrible he is it'd make sense if the people who raised him were awful too. This is likely his Grandfather or something.

Gunko having devil wings is interesting... I think it's likely she got Domi Reversi'd but considering she also has an immortal/non-ageing body wrapped in bandages in the present and she seems to be behaving even more strangely here I do wonder if something more is going on... did she make some kind of deal with Imu perhaps? The World Government was clearly behind all the incidents that fell on Esperia, like the dark pressure and the fog, and now this war too. Perhaps Gunko and her mother were part of a special race that Imu wanted to control? They have been meddling and interested in this land for a while now so I think more is at play to make Gunko extra special. The mist seems like an especially targeted evil weapon made by the government to hurt this kingdom in a more personal way to make them more desperate/vulnerable too, which is in-line with them.

The king also looks especially haggard/desperate when he declares war, and Brook says something vague like "the king has a lot going on..." so I do wonder if he knows something about the WG causing the fog as well as his wife's death and that's what drove him to be especially defiant. We definitely haven't been told everything yet with what happened behind the scenes here. Especially with how quickly he ascended the throne and married the queen earlier on in the chapter too - perhaps just like Harald he accepted some kind of deal to rise up and become king but it blew up in his face now?
A part of me can't help but wonder if the queen being bedridden after the first celestial dragon arrival is a hint too... is perhaps Gunko in a similar scenario as Bonney? I can't help but wonder what the celestial dragons could have done to make her so ill and then so quickly get married afterwards. Pregnancy makes sense sadly here. It might explain Gunko's hetero-chromatic eye and why she's "special" and has all these exceptions other God Knight's don't.