You're joking right?

If this were for research to solve diseases or help improve medicine, or elongate human life, maybe I could accept there being some value to this. Still immoral from my perspective, but perhaps subjectively valuable. For AI? Completely immoral

well when you say it like that lol... The human part of it, it's just brain tissue, sure there would be issues if it were to be described as "sentient" but I don't really think that's the case necessarily for just stuff being grown in a lab. These aren't fully formed brains, just pieces. And on the AI front, I'm pretty skeptical that this is the "world shattering" importance that its backers ascribe to it, but it's undeniably now an important part of the global computational infrastructure, and will be for some time. SO in the big picture, since (LLM-type) AI's are basically just neural networks, and if there's some way that brain tissue can be "trained" to produce something that mimics neural network outputs... Then I'd say this is worth exploring in a limited (scientific) sense, keeping in mind ethical constraints of course. And yes there's a "mad scientist" quality to it that I can't say I don't find exciting. 😃

Improved cancer screening due to machine vision is the only such example I can think of. And even in that case, the human doctor is the most valuable part of the chain

Science needs a purpose. The purpose of science has always been to understand the natural world to get closer to God and His Creation. I love science, I didn't spend 6 years of my life reading physics for fun before getting a real job for no reason. I loved it. Can't say that the degree was useful (toilet paper would've been more useful), but I can't say that I didn't enjoy it. I think there's incredible value in science, and I think that anything that improves our understanding of how the world works is a worthwhile pursuit no matter the material cost. But this? I can't agree to this on a moral basis. There's a quote, that I usually disagree with, but fits here: "they were so preoccupied with figuring out if they could, than thinking if they should"