so when you are at the part where you have two options on where to go. either the purple gate or orange gate. and infront of you the blue one is there, so when i tried to balista boost toward it and hit it it boosted me up the air so possibly we can skip the door by going to the final boss from the jump, i dont know if this can work but i am optimistic

Unfortunately the boss isn't available unless you go through the room that starts the boss fight. That said, any% currently just slopeboosts to that room anyways, not much faster you can get than that :P

you can enter the elevator