Which value chain activity is concerned with the availability of service components?

The Obtain/Build activity is responsible for ensuring that all service components are available when and where needed, and that they meet the agreed specifications.

https://www.beyond20.com/blog/what-is-the-itil-4-service-value-chain/#:~:text=The%20Obtain%2FBuild%20activity%20is,they%20meet%20the%20agreed%20specifications .