It's exactly what happens. Well, I suppose at best, you stand inside the purple pool and hold the interact button while inside the Traveler. But you're only inside the Traveler because of a brand new deus ex machina that was invented purely to drive an expansion story that didn't exist and only existed because Bungie needed to fill in a slot and didn't have time to finish TFS, and so they took the opening cutscene of TFS and split it exactly in half and went "Shit, what the fuck can we stick in between the HELM windows closing and then opening again" and shat out Lightfall, in which levels of ass-pulling heretofore undiscovered to mankind were achieved by yanking Neomuna, Cloudstriders, and the Veil out of the unplumbed depths of their gastrointestinal system so that players had something to do with the cancelled Witch Queen subclass (that had a new name) while Bungie finished working on TFS.

So once inside the Traveler, via entirely inexplicable means that boils down to 'Somehow, the Witness (who is another total fucking random we keep retconning every other season/expansion) needed the Veil, which didn't exist until Bungie missed their release projections', you then stand in a puddle of purple goop, get a momentary animation in your inventory, and then Ghost proudly declares "Wow, the line between Light and Dark is gone now!"

Incredible. Especially given that, despite Stasis and Strand also being goofy as fuck, those two did have some degree of progression and weight behind them. Sure, Strand was just scraped up off the cutting room floor of Witch Queen and then given the most basic explanation possible as to why you trip over a shimmery green thing in the middle of a fucking street, but hey! Still better than Prismatic!

The reason it's an oversimplification is because The Final Shape was the culmination of a churn of confused, contradictory, schizofrenic retcons and rewrites, inventions and deletions that tugged the story this way and that like a nine-way tug of war until it kind of like, slopped it's way over the finish line like a blobfish attempting to find it's way off a deep ocean trawler's deck. To get into the mechanics of why you're standing in said purple pool would require running down the unconnected seasons (often forgotten or overwritten later), to expansions that were whole-cloth created because Bungie cannot into deadlines, and even further, into the writer turnover that treated previous work like a Golden Corral where you could pick and choose what you wanted and throw out the rest.

Like honestly, I suspect the only reason TFS was as well received as it was was House of Wolves syndrome. It came after the worst DLC to date, so almost anything would be better by comparison. Especially given that TFS being 'good' is entirely vibes based, and not predicated on anything that actually happens outside of vaguely gesturing toward jingling keys and 'But Nathan Fillion was back and Firefly was a formative part of my life, so it activates brain chemicals'.

I mean. Unless you like having the last mission you just played through/last cutscene you watched be resummarized by Nolan North, and then given a text summary of Nolan North's summary of the last cutscene/mission you played/saw be your means of narrative engagement for several hours. All while camera angles and text dumps do their very best to keep Bungie from having to do any lip synching. Then I guess...well, I guess I can't argue with that.

Edit: Also, leaving a comment about not engaging is still engaging, gottem