I am running VirtualBox 6.0.8, with Extension pack added for USB 2.0/3.0 support.
I can get through most of the install process with JetPack after a whole bunch of mucking around with OpenJDK bzip2 etc.
During install it sees like the COM port drops out and then lots of flash errors happen in the terminal window - even after i re-mount the device in the VM.
Do I need a 2nd machine running Linux natively? Or can anyone confirm that they were able to flash using a VM based approach?
In general, yes, a native Linux machine is recommended, because the Jetson will change its USB device descriptor when going into recovery, which means the host will re-enumerate it, which means the VM will generally not see the new device.
It may be possible for you to configure the host and the virtualbox such that the new recovery USB device is always forwarded to the VM, just like the initial serial device, and if so, you might be able to make progress, but in general, the recommended setup for development is to use a “proper” linux workstation. (Or Linux partition to dual-boot from.)
I was able to use the prior release of JetPack (4.1.1) with a Linux VM and get through the process, but it is certainly not a straightforward process by any means.