I actually found the Joi subplot the most interesting part of the film, for that very reason. Did she/it have any free will? Or was she simply a very clever program? The bridge scene seems to want us to believe the latter – and at that moment, K seems to realise for the first time that it’s the latter – but even after that point, I’m not convinced.
The subplot is the film’s most direct callback to the original’s theme of what it means to be human, looked at through a new prism.
She was more of a slave than Roy Baty ever was, apparently incapable of rebellion, and dying (or choosing a path likely to lead to her death) rather than abandon her “master”.
Would she have passed a V-K test? Unlike Baty, she appeared to show empathy, to the extent of sacrificing herself to help another being. But was it “real” or programmed? Does it matter?
Was the path she chose (to her inevitable death) a programmed imperative or free-willed choice? Does it matter? “Dying for the right cause is the most human thing you can do.”