>>25655379
Back in the day I did some numbers on industry profitability derived from produced value in money equivalent and comparing to inputs value plus the cost of sustaining the workforce.
So, some goods are always profitable, some are shit no matter what you do. Food, alcohol, clothes are good, fuel and bitumen are very good, plastics are bad for exports etc. All building materials make little sense to export unless you want to compensate for some imports, you can even export gravel, but you need trains to justify that.
Nuclear chain is almost cheating, as Uranium is one of the most profitable goods.