Right, but doesn't it also provide some very basic level of abstraction that things like network stack implementations can target? And then many projects also come with their "standard" (not bundled, just designed for) set of basic libraries? That's the impression I'm getting from skimming through the docs. (https://docs.zephyrproject.org/latest/guides/networking/net-..., https://www.mbed.com/en/technologies/security/mbed-tls/, https://docs.aws.amazon.com/freertos/latest/userguide/freert..., etc.)