Yes, TLS for example uses X.509, as do lots of things. The container format, as well as the data-structure. I'm saying not just for SBOM, but for the code-signing cert aspect as well. I wouldn't mind if there was an "SBOM" usage in X.509, and CA's sell SBOM signing certs or whatever, but the sad fact is, I think some mobile platforms, macos and windows are the only place this is used.

We need for data-at-rest, what TLS has been for data-in-motion.