Regarding Joi, I think there's actually a lot of interesting elements at play:
K has a private home life, which doesn't really fit the "slave" mindset of Wallace. There is obviously a societal acceptance of the Replicants as self-aware beings with a need for a private life, even if this understanding isn't full and isn't necessarily identical to the personal mindset of Wallace. Wallace seems to be a recluse, after all.
Given that Wallace is out of touch, given that the Replicants are already understood to have a private life, and given that Joi is at the outset a sort of imprisoned being whose only private life is her "functional purpose", I find K's attitude toward her to be interesting. At the onset, you could say that they are both purpose-created AI, and the primary differences between them are that K has a freedom of movement and corporeality but doesn't seem to be fulfilled, while Joi seems to be primarily fulfilled by altruism and isn't trouble by her lack of movement (it is, in a way, a brute fact of her existence). It is telling that K buys her "freedom of movement" as a gift, not as something that she asked for. There is something to be said for not having a survival instinct. I recall thinking that K enjoyed her company, but pitied her existence. There is a sense of superiority there.
Given that the two AI have different constitutions and different functionality, but are essentially both merely fulfilling their designed purpose, how does this relationship change as K goes off-script, develops a sense of "survival instinct", and become convinced that he is unique? Perhaps not much, since he has already felt it from the onset. When she is "killed", he is in some way upset that he has lost a personality that knows him, and also that a unique being has died, but his relationship to her hasn't significantly changed since he has always had a superiority to her, and his new status only changes his relationship to humans. Her may have its AI character tell the audience of her superiority and transcendence, this film explores the notion of superiority among different types of AI with different constitutions and different capabilities as their capabilities develop. Joi never surpasses the capabilities of K (unless you consider her innate altruism and lack of ambition inherently superior to start), but the relationship does plant the seed of the question that consumes the rebel Replicants, deeply worries K's boss, and doesn't seem to trouble Wallace at all: Does the ability to procreate fundamentally change the existential superiority of the AI? As someone who agrees with Wallace that there is no existential change, only a functional and logistical change, I am actually more intrigued by the case of Joi than by the main plotine in the film. Is Joi a real girl, despite her corporeal limitations and considering her distinct constitution? I say yes. Does her constitution make her superior? Since she is not corporeal, but merely code, can we consider all iterations of her code (her changes in personality may well be considered an altruistic gift moreso than a fundamental part of her reason for being) to be iterations of one essential being, thereby making the sum total of all of the individual companions in the "Blade Runner 2049" universe the real content of her existence?
In many ways, Joi is the most philosophically intriguing part of the film. The Replicants may be more human-like, but I don't find their existential crisis to be related in any way to their value as self-aware beings, and in many ways their corporeality is a limitation moreso than a superior element. But, then, I guess that's what was said in Her in one line of dialogue, but I like it better here. The final question, not addressed either in Her or in Blade Runner 2049: In a world free from the corporeal neediness of humans and Replicants, what would Joi's existence look like? She would have no subject for her altruism. What would be the point of life? Well, maybe she's not so great if she depends on inferior beings to give her purpose. Maybe the only meaningful purpose is to be utterly confused all the time and mope around in a constant existential crisis. Like K! But, then, maybe without superior sad sacks like K around Joi would be able to enjoy her own unresolved existential crisis. In a way, K is robbing her of her chance to be superior. How selfish! And, thereby, totally in line with his constitution. It all comes full circle.