I think you are under thinking how much effort there is to "make it an immersive experience." The /vast/ majority of game travel time is always with characters

I think you are under thinking how much effort there is to "make it an immersive experience." The /vast/ majority of game travel time is always with characters that are running. It is a bit of a gag in games. Try using the characters at walking speed. And then think of transferring that to "we want you to feel like you are in a vast world.... that you can physically traverse in less than a day. Probably less than an hour."