Should the eMMC be visible in /dev?

When I put the TX2 in recovery mode, I’m able to see it via lsusb, but I can’t find the eMMC in /dev (there is no mmcblk0p1). Is there something wrong with it?

In recovery mode the TX2 is a custom USB device, not bulk storage. I think a lot of phones and music devices out there have fooled people into thinking the type-B USB connector turns the device into bulk storage, but that isn’t the case…it is custom to the particular device. There is no possibility of turning a recovery mode Jetson into bulk storage. The “driver package” (which is downloaded by JetPack or SDK Manager) understands how to talk to the custom USB device.

So you need to use SDK Manager (or JetPack for older releases) to work with the Jetson in recovery mode. These run on an Ubuntu PC host.