You don't necessarily need any physical commodity to back your fiat to have it become valuable. The most important thing that can back the fiat is the economy itself. A healthy productive economy is worth a lot more than all the resources.
Take the Chinese economy for instance. It has issues but it is still the strongest and healthiest economy in the world. They don't even have enough resources to back that massive economy and yet it is massive and strong. Why? Because they are producing actual goods for an actual demand that exists.
Other economies that face issues (and consequently their fiat), are facing them because their economies were not healthy. A lot of them were based on debt and you can only keep a debt based economy running for so long before it falls apart.
The Chinese don't have enough resources? Where did you get that information? As far as I know China owns many resources/mines in Africa nowadays and they have good relations with Russia that is also big on commodities.
Let's see what Investopedia says about that:
https://www.investopedia.com/articles/markets-economy/090516/10-countries-most-natural-resources.asp10 Countries With the Most Natural Resources
1. Russia
Russia's natural resources reserves are worth $75 trillion by Statista's estimate. This amount incorporates, among other things, coal, oil, natural gas, gold, timber, and rare earth metals. Russia's Ministry of Natural Resources and the Environment estimated the total value of the country's mineral reserves at the end of 2018 to equal $1.44 trillion. U.S. Geological Survey. "2019 Minerals Yearbook."
2. United States
The estimated value of natural resources in the U. S. is $45 trillion, almost 90% of which are timber and coal. In fact, the U.S. is the leading producer of coal. As of 2020, it had the largest proven coal reserves in the world.
3. Saudi Arabia
Saudi Arabia is a small country in the Middle East and is slightly larger than Mexico. Saudi Arabia has $34.4 trillion worth of natural resources—notably oil. The nation has been a leading exporter ever since oil was discovered in 1938.
4. Canada
Fourth on the list is Canada. This vast country has an estimated $33.2 trillion worth of natural resources. It has the third-largest oil deposits after Venezuela and Saudi Arabia. The commodities that the country owns include industrial minerals, such as gypsum, limestone, rock salt, and potash, as well as energy minerals, such as coal and uranium.
5. Iran
Iran's natural resources are worth an estimated $27.3 trillion. In 2021, this country was the fifth-largest crude oil producer in the Organization of the Petroleum Exporting Countries (OPEC) and the world's second-largest natural gas producer. [13] Other natural resources include coal, chromium, copper, iron ore, lead, manganese, zinc, and sulfur. Arable land, pistachios, saffron, and fruits also contribute to the estimated value.
6. China
China has natural resources estimated to be worth $23 trillion. Ninety percent of China's resources are coal and rare earth metals. Timber is another major natural resource found in the country, as is arable land.
(the list goes on)
$23 trillion in natural resources, 6th richest in the world, is definitely not as bad as you pictured it. Especially when they have a friend like Russia that is the richest country with the natural resources.