While messing around in the game, on Floor 15 of the Final Sword Trial, I ended up getting clipped through the wall by being hit by a spear bokoblin's spin attack while backflipping, toward the corner closest to the entrance. Either way, I didn't have any video recording active at the time and booted up OBS to capture it after already clipping through the wall, but in this big meandering video I eventually found out where the final Sword Trial room is and how to enter it, which let me skip Floor 15 all the way to the end (and kill enemies in the final floor from outside the room).

Final room's found around 6:30, and the clip into the room is at 21:56 or so. All I did was whistle-run through the right spot.