This is the Unity, some kind of center of everything, that you've been working towards reaching by gathering all the artifacts and defeating you competitors, the Starborn.
In the Unity you meet...yourself. Or something that looks like you, anyway. It doesn't tell you anything, really. This is the Unity, it's nowhere and everywhere at the same time, yada yada.
You actually get a choice, after you've been here to just go back, and continue playing, and then come back anytime you want to restart. Some of the other members of your team, Constellation, are coming with you to the Unity, though you never see them aboard the ship or inside the Unity itself. If you do decide to go back, you will find that all members who decided to go came back with you together, and you can get some nice dialogue from them. "Man, we all decided to come back, huh? Come on, we have to go for realz this time!" It's a nice touch, and allows you to keep playing with them until you're REALLY ready to go.
I'm not gonna scream woke, but does this think look like a female egg, and you're supposed to be a little sperm quivering infront of it? Well, anyway, inside we go.
We get a little cutscene that slowly zooms out from our galaxy...
And then we see what is supposed to be the universe, or the multiverse? Something like that.
And then the credits roll, which you can skip after a few seconds, presumably after everything is done loading.
And, we're back on the Starborn Guardian. We've lost all our posessions and are ready to start anew, incrementally increasing our autistic superpowers...
The End... for this universe, at least,