Some time ago all of the NVIDIA files used were just that…loose files, and not available as a package. This meant that any regular packages from Ubuntu had to be skipped if they would have overwritten this content. Then NVIDIA built their own package-based repository server. When that server is available it means updates can occur with apt even for the NVIDIA packages (which are now actual “.deb” packages and not loose files). So “Over the Air” (“OTA”) is basically setting up Jetson updates to more or less be mostly using the “standard” apt-get mechanism.