JetPack is a front end to the installer software, and does not take part in a running system.
JetPack itself requires x86_64, it cannot run on other architectures (it is a foreign architecture to a Jetson). The software which performs an actual flash is x86_64 binary code, and cannot run on anything but a desktop 64-bit Linux PC (JetPack additionally requires a particular version of Ubuntu on the host, the driver flash software has less restrictive requirements when run by command line instead of the JetPack front end).
Since installer software creates a loopback image of the entire file system as a temporary file during flash, any attempt to run a flash from a Jetson would require the entire eMMC just for a temporary file…and then many GB beyond this for other files, such as the entire operating system from which the temporary file is created. You would have to not only port the flash software to run from aarch64 (not possible), you’d also have to put a very large (relative to existing eMMC) hard disk on the Jetson.
The only possibility for JetPack is to run from an Ubuntu desktop host. Running just flash can only work from a 64-bit Linux host.
NOTE: A host might need in excess of 25GB of free space to put in JetPack.
I do not know of all of the specific packages available through JetPack, but basically you run JetPack on your Ubuntu host and check options for packages you want (target TX1, not TK1 and not host…do not check flash and this will be a purely software package addition). There may be other setup such as network address if this was not previously set up.
Someone else may be able to comment on specific packages. Note that there are some options to manual install of packages without JetPack, but I would not advise it unless you really need to go that route. In other cases packages managed by the apt package manager front end may apply as per any Ubuntu system admin documents describe…some packages are specific to NVIDIA, others may be available over the internet outside of JetPack.