focus on the amount it costs to produce 1 BTC in terms of mining costs, what is that value and how do we calculate that?
Bitcoin is not a product that means that bitcoin price is not decided by its production cost.
I feel that just saying that Bitcoin is not a product doesn't really explain it. The price of a bitcoin is not influenced by its production cost because production is fixed. Producers (miners) can't adjust production in response to price, so they have no influence over the price, in contrast to most other products.