This pack is quite simple. It allows players to traverse between the overworld and end dimensions as if the end is above the overworld, like space.
The primary way to travel is via elytra and firework rocket, once you have already reached the end via traditional means.
It also means any poor soul that falls off the end islands wont lose all their gear to the void, but will fall to their demise somewhere in the overworld. Or perhaps get lucky with water.