I see what you mean, for summary a guess a general sum of revenue vs expense should be OK using account transactions.
If you want specific metrics for cost of goods. This would be a good place to start looking
Custom Report Tag engine should allow you to sum and group it as a separate line in your report.
Something to keep in mind is that you would need a very detailed recipes for Cost of Goods to be very accurate, otherwise should always be considered “Estimated Average”.