in the fall there is a skip right before cave Johnson's introduction where you jump on a railing and you shoot a portal at a place farther into the level, this portal-able surface isnt shootable on switch due to it being too much behind the rocks, are there any alternative skips?

I don't believe there is any physical difference in the map, however, if you watch the tutorial you would see the skip labeled "Beginner Mid Map Route"

thanks!