I would probably keep the train still and then spawn tiles in front of the train that move past it and eventually despawn, creating the illusion of moving forward.
I don’t know how to make it be procedural though, I would probably make varied tiles and then spawn them in a random order, creating enough variation that you won’t think too much about it.
I guess it depends how much the game is about actually looking out the window, if it’s just meant as background I think it could work well enough?