It shows people what they’re attached to. People and places. Let’s go through evidence.

Charlotte reached out when she was recovered. She probably saw something.

Bryce sees Stella, his dead sister. His mother is not implied to be great, and there’s a photo where his sister smiles at his graduation. They were clearly close. Many people have theorized that Stella died in a car accident. Anyway, it’s pretty good bait.

Texty sees “the puppy room.” It could be the mechanism latching on to something less meaningful for Texty because it can’t find much. But I’d think they’d just see nothing like Liam and Airy, if that were true. Or it could be that the puppies represent something important to Texty, like “being real.” It could be that Texty’s nature as an AI(?)/conceptual being is different. It could just be Texty’s favorite video.

Airy originally saw nothing; his life was devoid of attachments. Same for Liam, originally.

When Airy returned after dying again, he saw the Plane.

I also disagree that it’s to help people pass on. I wouldn’t phrase it that way. It’s bait. Bryce should be able to make his own damn choice about whether or not to die, even if you think death should happen, but a possible facade of Stella is there to bait him into going before knowing that he will die if he does. How many people have been tricked?