I don't think GDP per capita is meaningful for discussing this, precisely because of the "allocation and efficiency problem" you pointed. It's convenient to me

I don't think GDP per capita is meaningful for discussing this, precisely because of the "allocation and efficiency problem" you pointed. It's convenient to measure whether food production would theoretically be enough: take the quantities an adult need, count the throughput of optimal production of proteins, carbs etc. The cost however is meaningless because most of what we spend on is transport, marketing, storage, packaging, shelving, etc. that's what we count when we say that a household spends x% on food. We can do the same for the volume of T-shirts, sqm of housing, etc.