Hi mmmysl,
You can use TX/RX cable and connect from J14 pins on Xavier-NX to USB port on your host mahcine.
[J14]
Pins 3: RXD
Pins 4: TXD
Pins 7: GND
And check “ll /dev/ttyUSB*” on your host Ubuntu machine and using picocom or minicom tools to open uart log.