eMMC Jetsons (including Xavier) are flashed when in recovery mode. Recovery mode turns the Jetson into a custom USB device understood only by the “driver package” (JetPack/SDK Manager is a front end to this). JetPack/SDKM runs only on an Ubuntu 18.04 host PC (command line flash without the JetPack/SDKM GUI runs on any Linux PC). The driver package does not run on Windows, so you are out of luck.
Some other Jetsons boot from an SD card, and those have available a sample image which can be directly added to an SD card from any host of any o/s, e.g., via Etcher on Windows or via
dd on Linux. Xavier is not an SD card model, it uses eMMC.
A normal flash to eMMC uses several tools which are not available on Windows even with WSL, e.g., loopback.
Some people use a VM, but this is not necessarily an easy route since USB has to be set up right and there may be a learning curve in that.
By far the simplest route if you want to develop is to dual boot with Ubuntu 18.04.