I've been doing a little rough doodling on the map of the route that they took in the Sun and Moon demo, and it's a little surprising, honestly.
1 is the starting house.
2 is where you battle Ledyba and Yungoos.
3 is where you battle Lass Audrey.
4 is where you battle Youngster Oliver.
5 is where you battle Pikipek and Yungoos.
6 is where you meet with Hau, Hala, Kukui and Lillie.
7 is where you battle Hau.
First and foremost, I did not expect that building to be your house. It's massive, and pretty isolated- you don't seem to have any neighbours- there's a Pokémon Centre across the street, there's the trainer school beyond it, and Kukui's lab is further down on the beach. It isn't, however, just isolated- the presenter refers to you travelling to the second town to take part in the festival, implying that where you live counts as the first town. Obviously your house isn't going to constitute a town by itself, but what else is included in that- Kukui's Lab? The Pokémon Centre? The training school? Hell, is there even a division between the starting town and Honolulu?
Anyway, you take a left out of your house, and follow the coastal road up and around the back. This is interesting in itself- the road doesn't seem particularly passable on the drawn map, and none of the details on what is a particularly important route are actually featured. Indeed, some of the details are actively wrong- just before the point where you battle Audrey, you pass through a part of the route that's blocked off by a fence on the map. It seems likely that Route 1's actually two branching paths that meet up together at that point- considering we've seen footage of you receiving your starter from Hala on the stage in the second town, I'm going to guess that heading right from your house allows you to use a road without any wild grass on it. This will probably have to be changed for your first time up, however- considering where Oliver's placed and the long grass behind him, there doesn't actually seem to be a way to get to the town without a Pokémon battle. Maybe Oliver isn't actually present the first time around, or Kukui accompanies you in a way that doesn't allow you to battle him?
Looking at that second town, it should be obvious (if it wasn't obvious before) that the drawn map wasn't all that detailed- buildings are mostly in the right places, but there are several cosmetic details, burning torches and stands surrounding the stage which aren't even hinted at in the artwork. Here's also where we get English confirmation of the first island's name- it's Melemele, which a quick Googling tells me is Hawaiian for yellow.
As for actual character details, Lillie is fleshed out a little more. Most importantly, we know that she doesn't take the stronger starter to you- although she apparently has a Pokémon in her bag (or maybe even as the bag), it doesn't make the same phonetic sound that we saw Rowlet make back in the reveal trailer. Hala, meanwhile, is described as one of the strongest trainers on the island, so we will presumably be battling him at some point- a gym leader or Champion, maybe, or even just an optional postgame trainer. I'd hazard a guess that he lives in that big building by the stage- a possible gym to return to later? Hau is referred to as the "grandson of the kahuna"- as Hala says this, he probably isn't Hala's grandson- I'm guessing we'll meet Hau's grandfather at some point.
As for Tapu Koko, I'm guessing it's a guardian legendary with a counterpart on each of the islands- think Mesprit, Azelf and Uxie back in Diamond and Pearl. It's explicitly called a "curious little thing," but it doesn't seem to be all that mysterious- the woman in the crowd says that appearing in front of the player character is "just typical of it"- maybe it's a rare or even unique Pokémon without actually being a legendary? Hell, maybe it's actually Rotom, and that's where the Rotom that goes in the Pokédex comes from? You have to get the Rotom soon- you explicitly haven't got it at the point where this demo takes place, and have it by the time you get back down to the Trainers' School, as per the Rotom clip from a few weeks back. I'd say this is unlikely, though- I've read that Tapu Koko is Maori for "sacred bird", which seems a little more on-point for a guardian deity.
I didn't like how many old Pokemon were in the demo. Hau has a Pichu? Why?
Probably because it's an Electric-type that can be caught on Route 1, and they needed to give him something strong against Popplio for the sake of the battle.
