"A supply chain is a network of individuals and companies who are involved in creating a product and delivering it to the consumer. Links on the chain begin with the producers of the raw materials and end when the van delivers the finished product to the end user. "
https://www.investopedia.com/terms/s/supplychain.asp
The exchange of money, guarantees, quality assurance... None of it is required.
The last node in the supply chain for virtually any real-world product is "human beings extract the material from the earth in some way/shape/form". No human being paid "the earth" money for this, yet it is a fundamental component of supply chains (and, recently, a fundamental component of many supply chain issues). "The earth" also doesn't offer any guarantees or quality assurance.
Attempting to interpret these processes as requirements to be part of a "supply chain" excludes the core foundation of traditional supply chains.