Henadic Theologian
Legend
It's not a contiguous open world game like Witcher 3 or Skyrim. The datamined map is for overland travel, and may well be just for Act 2. It doesn't represent the limits of the locations that can be visited in the game (it doesn't show Avernus for a start).
The Throne of Bhaal was a decidedly epic level level adventure, ending in becoming a God, but it had the smallest regional map. The Baldur's Gate games have never been about going wherever you want, you only go where the story gives you reason to go,
No overland travel to Baldur's Gate is still act one. All travel TO BG is act one, because BG itself is Act 2.
Stuff being added to Act 1 that never appeared in EA include Moonrise Tower, Lae'zel's Creche, Kenrith City, etc...
Its unknown where Act 3 occurs, same say Hell, some suggest Candlekeep, Chult is very possible, but if my guess is right, then the visiting circus to BG could be the Witchlight, which opens up the possiblity of the Feywild as well.