It’s achievable. It’s called “direct indexing”, and there are some extra costs associated with it, so for most investors, I think it is cheaper to get QQQ. You can flip that around with tax loss harvesting but I don’t understand that strategy and I can’t explain it.
You also don’t need AI to do this. Before AI, the main barrier to direct indexing was the amount of capital you need. That is still true.
I have enough capital to where I can do everything with the incremental share threshold of Interactive Brokers; as such I don't have to deal with the fees associated with normal direct indexing.
Still, as you said, just mimicking regular QQQ is achievable.