Commodities. Raw materials with which all goods and services are made. Coffee, sugar, wheat, pound of beef, gasoline. Also products which are supposed to be identical like a Big Mac. Purchasing power is hard to measure but it’s a question studied deeply by economists.
Even the Big Mac index is flawed because it's not quite the same burger, since it's not made in the same regulatory environment, or by people compensated equally fairly.
No, my point is that there is no such thing as purchasing power. An iPhone doesn't cost less in China or India even though their "purchasing power" is much higher on paper.
Having "high purchasing power" just means that you have access to low quality options that people in "low purchasing power" countries don't because there isn't a market for it.
A neighborhood with just a Walmart doesn't have higher purchasing power than a neighborhood with just a Whole Foods.