Any non-VM 64-bit Intel architecture works. Basically, any Intel or AMD CPU. To flash on command line most any Linux distribution works. To use the graphical front end, JetPack, you’ll need Ubuntu. Earlier releases may have preferred Ubuntu 16.04, but I suspect 18.04 works now.
If you wish to install some of the software and tools on the host itself, then you’ll need a semi-modern NVIDIA graphics card. Even if you don’t have NVIDIA graphics on the host you can still install to the Jetson without issue.
The one resource flash is most hungry for is disk space. Once your operating system is in place you might consider that at a minimum you need another 30 or 40GB. The actual images are literally clones of the entire eMMC (which is 16GB). Then it builds a “sparse” image. Other files are used in creation of the image, e.g., all files of the root file system. You will want enough disk left over with everything there which is why I suggest at least 30 or 40GB spare. In reality, if you wish to clone as a backup mechanism, you’ll want perhaps double that…having 60 or 80GB free disk would be a good idea. Other than this you don’t need many resources to use JetPack (not sure on RAM, but probably 4GB would be fine; you need a wired network connection).