Yeah this is part of the problem.

But even if you had like 10M rows of pricing and then gave a 2% discount to entity A, 3% discount to entity B, 4% discount to C, etc.

You could publish these discount rules.

Or you could just multiply the 10M rows by the number of different entities giving 10*n M rows.

And then let the consumer of the data try to figure out the rules from the output...?

It would be interesting to see whether it's possible to reconstruct the rules by comparing the negotiated prices to a baseline like Medicare price, and doing classification into discount buckets to recover the categories insurers negotiated.