This tells me it wasn’t real.
A clue as to whether Deckard is ‘real’ or not: when the bad guys from Wallace come to take him away, they are all wearing some kind of respirators presumably to help them breathe in the hostile dirty-bomb Vegas environment. Deckard doesn’t need one of these to live full-time there. K doesn’t need one either.
Although on the other hand, the Wallace baddies are 99.9% probably replicants as well. So never mind.
The irony/sadness of a replicant forming a relationship with a ‘massclusive’ lower-level “ones-and-zeros” AI was really nailed home in the scene with the big pink holo-projection. I’m not any kind of Gosling fan, but his under-stated delivery really made me feel bad for his character.