I dunno if it has been said already but the architecture seen in the trailer is not boiding well for this game having more than one city.
The big city they shown uses both Barcelona and Madrid's architectural styles, and the vegetation is based on the Valencian orange orchards. So there they go the 3 major spanish cities. Then the outside houses are based, at least the interiors in andalusian houses, so Seville/Cordoba is also represented.
You can see also a part of the map of the region during the trailer were Galicia is, and is a huge swamp (probably the one in the trailer were psyduck appears).
Maybe theres some super small towns dotted around the map but something tells me this is using the arceus method and only having one big base city. (I think what appears to be names in the map are openworld regions names and not town names)
Hopefully im on the wrong here.
Also about the starter animals, seems they are based (sprigatito is 100% clear at least) im 3 spanish animals from what people are saying in the internet.
Sprigatio is a iberian lynx
Fuecoco may be based on giant lizard of tenerife
And quaxly may be based (although this one seems the less likely) in a male red crested pochard (while is a very typical duck from spain it can also be found in other parts of the world, thats why i think this may not be based in this animal. I just think its based more in how some spanish people dress here, just like the rabbit in sword and shield looks like a football player.
Probably more interesting is the shots of the real part of the trailer were so much emphasis is put in oranges and wine grapes, which i think is an indication with the titles of what we are gonna be getting with the legendaries
Those 2 shields in the last screenshot with an orange and the other with the grapes are particularly interesting.
Also im seeing a lot of comments this could be based in the iberian peninsula as a whole, but the map shown in the real part of the trailer is cutting exactly portugal out of it, so i dont think anything about portugal is in this game.