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.
What you are asking only works for products, like a car for example. They have a production cost and that decides what the finial value of it is. But in case of bitcoin the only deciding factor is the utilities that bitcoin provides and the supply & demand (or adoption) of it.
Even more interesting is that for bitcoin the "production cost" (ie. the mining cost) is decided based on bitcoin's price not the other way around.
But even the value of a product isn't based fully on production cost. Take GPUs, for example. It can cost, say,
$400 to manufacture (including salaries and stuff), it can allegedly be sold (MSRP, I mean) for $750, but actually cost
$1800 on the market. So even for products there's a great gap between the production cost and the product's value. So with Bitcoin I guess it's just exacerbated because the demand and supply play an even bigger role, but it's not like a product is defined by its production cost either.