Ask Lemmygrad

Many nations, even capitalist ones, have state-owned enterprises. A large percentage of trade deals in this century are free trade agreements or tariff reduction negotiations which involve no material goods but these aren't the only types of trade deals.

The US likes to make deals trading ownership of mineral/oil extraction rights to American corporations for US military support (read: a shakedown). Western countries use debt as a weapon with tools like the IMF and World Bank. "Give us your cash and minerals and neoliberalize your economy or we kill you. You're now in debt. Be glad we're not still colonizing you the old way."

China has been making a lot of deals that break the mold of Western deals. A recent-ish example is paying off Ghana's loans from Western countries and refinancing at a lower interest rate; duty-free entry (no tariffs) on goods from Ghana exported to China; and building infrastructure like around 442km of roads, plus bridges, schools, hospitals in exchange for around 5% of Ghana's refined bauxite production.

You get: Roads We get: Bauxite

Bridges‎ ≤100% ROI on loan

Schools

Hospitals

Lower interest rate

Doesn't the World Bank offer some services of guarantee to nation states ?

You're right, these countries don't have direct materials sitting somewhere in a warehouse. These trade deals, thus, usually don't deal with direct exchanges of good.

Instead, the thing exchanged is usually promises or services. For example, "if you build additional power infrastructure on the border, we will provide zero-interest loans to the construction companies". Or "no tariffs on clothing and food for both our counties, ok?"