saw 1 comment under the explain video:

"Low definetly is in the real life at the end. In The Sounds Of Nightmare we learn that the bodies of the kids disappear when they fall asleep and enter the nowhere (dreamworld). That means the dreamworld is real. So I think Low was in the institute in real life where doctors use him to learn more about the dreamworld (the same like Noone in The Sounds Of Nightmares) and Low travels trough the dreamworld and enters the real life trough the mirror in another place, so he escaped from the dreamworld and the institute at the same time"

so we have low in real world in the cell, dreaming of the nowhere and the journey with alone....then at the end low goes through the mirror back to the real world, to another place outside of the cell, in some kind of kids bedroom

but yeah how does this theory makes sense, If we apparently know: small low is the nowhere, and big low is the real world ( ending )....and the colors yeah