Is there some sort of multilevel KNN/ML model I can use to figure out which users will buy specific products?

I am wondering if there is some sort of multilevel model that I can use to identify likely buyers of specific products or create a lookalike audience.

The issue is that I have 1000s of products and around a million users. It would be computationally infeasible to create a model for every product.

The structure I am thinking of is the first level is a product and the next level is all the users in my database.

Is there some …

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