>>37951615The gym leaders in Kanto from Surge to Blaine could be done in any order, except Koga must be beaten before Blaine. Chuck to Pryce in Johto could be done in any order, and so could all the Kanto gym leaders.
That said, yes, "linearity" in games refers to the order in which you can do things, not the shape of the game's world.
>SM had optional areas just like the games before itThe only substantial optional dungeon is Haina Desert.