Some five years ago I was day dreaming about recommendation engine for movies where you could say "hey Ciri, give me a good gangster flick", and it will come up with something that you haven't seen yet but you'd definitely love.
To my amazement almost everyone, even true AI believers, thought it was impossible to achieve. :d
But my question is - having such huge dataset, do we really need AI for it? SASRec/RAG is sexy, but could the same result be achieved with simple ranking and intersections like lastfm did in the past with music?
Some twenty years ago I came up with an idea of "brain" data structure for recommendations where you have all your items (books, movies or articles) modeled as a graph, and whenever you pick something it makes a ripple effect, effectively raising scores in cascade of every adjecent item.
Just like your brain works - when you stumble upon something new it immediately brings back memories of similar things from the past. I never had the opportunity to implement it and test in real life scenario, but I'd be surprised if a variant of this is not widely used across different recommendation systems, like Amazon.